Triazolotriazinyl fused ring nitrogen-rich organic covalent skeleton as well as preparation method and application of triazolotriazinyl fused ring nitrogen-rich organic covalent skeleton

Abstract

The invention relates to a triazolotriazinyl fused ring nitrogen-rich organic covalent skeleton as well as a preparation method and application thereof. The structure of the triazolo-triazinyl fused ring nitrogen-rich organic covalent skeleton is as shown in a formula I in the specification. The invention also provides a preparation method of the triazolo triazinyl fused ring nitrogen-rich organic covalent skeleton, which comprises the following steps: polymerizing a 2, 6, 10-triformonitrile-tri [1, 2, 4] triazolo [1, 5-a: 1 ', 5'-c: 1 '', 5''-e] [1, 3, 5] triazine compound and a catalyst under the conditions of heating and inert gas to obtain a crude product; and placing the crude product in an acid solution or an organic solvent, and filtering to obtain the triazolotriazinyl fused ring nitrogen-rich organic covalent skeleton. The invention also provides an application of the triazolotriazinyl fused ring nitrogen-rich organic covalent skeleton as a photocatalyst. The invention provides a novel triazolotriazinyl fused ring nitrogen-rich organic covalent skeleton, so that a novel photocatalyst is provided. # imgabs0 #

Description

Technical Field

[0001] The invention relates to the technical field of organic compounds, and in particular to a triazolotriazine-based condensed-ring nitrogen-rich organic covalent skeleton and a preparation method and application thereof. Background Art

[0002] As the process of industrialization and urbanization in human society continues to accelerate, energy demand continues to rise. Traditional fossil fuels such as coal and oil are difficult to meet the needs of sustainable development due to their limited reserves and the large amount of pollutants produced during combustion. Therefore, the development of efficient and clean renewable energy has become a research hotspot worldwide.

[0003] Solar energy is an endless, clean and pollution-free renewable energy source. Photocatalysis, one of its utilization methods, has attracted widespread attention. Photocatalysis can drive chemical reactions through light energy to achieve energy conversion and storage. It has great potential in the fields of preparing hydrogen, hydrogen peroxide, reducing carbon dioxide, etc. Efficient photocatalysts are the key to realizing this technology.

[0004] As a new type of organic semiconductor material, triazolotriazine-based condensed ring nitrogen-rich organic covalent frameworks (COFs) show great application prospects in the field of photocatalysis due to their unique structural characteristics, suitable bandgap width and more nitrogen active sites. At present, C3N4 compounds (especially graphite phase carbon nitride g-C3N4) are typical representatives. Traditional C3N4 compounds are mainly composed of basic structural units such as heptazine rings or triazine rings. These structures give the materials unique physical and chemical properties and become one of the hot spots in photocatalytic research. There is still room for further optimization of their structure and performance. Researchers mainly focus on modifying traditional C3N4 materials to improve their photocatalytic activity and photocatalytic efficiency, but their performance improvement has not been obvious in recent years. There are relatively few studies on new C3N4 triazolotriazine-based condensed ring nitrogen-rich organic covalent frameworks with new structures.

[0005] The construction and synthesis of new nitrogen-rich fused ring compounds may bring new structural characteristics and properties to C3N4-type materials, and may also further optimize their photocatalytic performance by regulating their structure. Summary of the invention

[0006] In view of this, the purpose of the present invention is to provide a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton and its preparation method and application, so as to provide a new triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton, thereby providing a new photocatalyst.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton, the structure of the nitrogen-rich fused ring compound is shown in Formula I:

[0009]

[0010] Through detection and analysis, it is known that the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton of the present invention has a C3N4-type organic covalent skeleton with tri[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine and triazine ring structure, which breaks the current situation that C3N4-type materials only have two structural units, heptazine and triazine, making it have potential application value in the field of photocatalysts. And the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton of the present invention has a very high nitrogen content. The rich nitrogen element can not only improve the polarity of the material and enhance its interaction with specific substances, but also provide abundant active sites for subsequent modification or functionalization.

[0011] The present invention also provides a method for preparing the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton according to the present invention, comprising the following steps:

[0012] The 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound and a catalyst are added to an inorganic solvent, and a cyanocyclotrimerization reaction is carried out under heating and inert gas protection to obtain a crude product;

[0013] The crude product is placed in an acid solution or an organic solvent and filtered to obtain the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton.

[0014] The preparation method of the present invention uses 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound as a starting material, and forms a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton with high cross-linking and stability through its own direct polymerization reaction. This structure can resist the influence of various chemical and physical environments, and enhance the durability and service life of the material.

[0015] The preparation method of the present invention is carried out under the conditions of heating and inert gas protection, avoiding harsh reaction conditions such as high temperature and high pressure, reducing energy consumption and equipment requirements, and improving the safety and feasibility of the preparation process. At the same time, inert gas protection can also effectively prevent the influence of oxygen in the air on the reaction, ensuring the smooth progress of the reaction. The intermediate product is placed in an acid solution or an organic solvent for treatment, and a pure nitrogen-rich condensed ring compound can be obtained by a simple filtering operation. This post-processing method is simple and easy, does not require complex separation and purification steps, and reduces production costs and time costs. Because the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton has excellent structural stability and rich nitrogen content, it shows potential application value in multiple fields. For example, in catalysis, adsorption, separation, energy storage and conversion, etc., the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton can play an important role. In addition, it can also be used as a template or precursor for preparing other materials with special structures and functions, and has broad application prospects.

[0016] Preferably, the method for preparing the triazolotriazine-based condensed ring nitrogen-rich organic covalent framework comprises the following steps:

[0017] Mix 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound and catalyst in a certain proportion in a glove box, and place them in a crucible or ampoule with a ceramic lid. Then seal the crucible or ampoule, and take the sealed crucible or ampoule out of the glove box. If the reaction uses an ampoule as a reactor, the ampoule needs to be vacuum-sealed before starting the reaction. Place the treated crucible or ampoule in a tubular furnace, and vacuum backfill the tubular furnace with inert gas for at least 3 times. Heat the tubular furnace under an inert gas flow, and after the reaction, a crude product of the compound of formula I is obtained.

[0018] The obtained crude product is ground into powder, placed in an acid or an organic solvent, stirred for a period of time, and filtered to obtain a compound of formula I, i.e., a triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton.

[0019] Preferably, the catalyst is selected from at least one of trifluoromethanesulfonic acid, trifluoroacetic acid and potassium chloride-sodium chloride-zinc chloride ternary eutectic salt.

[0020] Preferably, the molar ratio of trifluoromethanesulfonic acid or trifluoroacetic acid to 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound is 0.1:1 to 5:1.

[0021] Preferably, the mass ratio of the potassium chloride-sodium chloride-zinc chloride ternary eutectic salt to the 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound is 1:1 to 10:1.

[0022] Preferably, the mass ratio of potassium chloride, sodium chloride and zinc chloride is 10:13:75. The ternary eutectic salt is in the form of mixed powder.

[0023] Preferably, the heating temperature is 200°C to 350°C.

[0024] Preferably, the heating time is 2 to 48 hours.

[0025] Preferably, the acid is selected from hydrochloric acid solution, sulfuric acid solution or a mixed solution of the two, and the concentration of hydrochloric acid in the acid solution is 0.1 to 3.0 mol / L;

[0026] Preferably, the organic solvent is selected from at least one of an alcohol having 1 to 6 carbon atoms and a nitrile having 1 to 6 carbon atoms;

[0027] The intermediate product is placed in an acid solution or an organic solvent, stirred for 1 to 24 hours, and then filtered.

[0028] The present invention also provides an application of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton as described in the present invention, wherein the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton is used as a photocatalyst.

[0029] Preferably, the triazolotriazine-based fused-ring nitrogen-rich organic covalent skeleton has excellent photocatalytic effects as a photocatalyst for preparing hydrogen peroxide, reducing CO2 to formic acid, reducing nitrobenzene to aminobenzene, etc.

[0030] Wherein, the structure of the 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound is as shown in Formula I:

[0031]

[0032] Through detection and analysis, it was found that the 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound has the characteristics of a two-dimensional planar structure, rich nitrogen content and three cyano groups. It can further undergo cyclotrimerization reaction and has potential application value in the raw materials of new carbon nitride triazolotriazine-based condensed ring nitrogen-rich organic covalent skeletons.

[0033] Beneficial effects of the present invention:

[0034] The triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton of the present invention has a C3N4-type organic covalent skeleton with [1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine and triazine ring structures, which breaks the current situation in which C3N4-type materials have only two structural units, heptazine and triazine, and has potential application value in the field of photocatalysts. The triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton of the present invention has a very high nitrogen content. The abundant nitrogen element can not only improve the polarity of the material and enhance its interaction with specific substances, but also provide abundant active sites for subsequent modification or functionalization.

[0035] The preparation method of the present invention generally uses 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound as a starting material, undergoes a direct polymerization reaction, and does not produce small molecular byproducts during the process, thereby forming a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton with high cross-linking and stability. This structure can resist the influence of various chemical and physical environments, and enhance the durability and service life of the material.

[0036] The preparation method of the present invention is carried out under the conditions of heating and inert gas protection, avoiding harsh reaction conditions such as high temperature and high pressure, reducing energy consumption and equipment requirements, and improving the safety and feasibility of the preparation process. At the same time, inert gas protection can also effectively prevent the influence of oxygen in the air on the reaction, ensuring the smooth progress of the reaction. The intermediate product is placed in an acid solution for treatment, and a pure nitrogen-rich condensed ring compound can be obtained by a simple filtering operation. This post-processing method is simple and easy, does not require complex separation and purification steps, and the auxiliary materials used are easy to recycle, reducing production costs and time costs. Since the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton has excellent structural stability and rich nitrogen content, it shows potential application value in multiple fields. For example, in catalysis, adsorption, separation, energy storage and conversion, etc., the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton can play an important role. In addition, it can also be used as a template or precursor for preparing other materials with special structures and functions, has broad application prospects, and has promotion and application value in the field of organic compound technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the solid-state NMR carbon spectrum of the triazolotriazine-based fused-ring nitrogen-rich organic covalent skeleton prepared in Example 1;

[0038] Figure 2 is an X-ray powder diffraction analysis diagram of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton prepared in Example 1;

[0039] Figure 3 is an X-ray powder diffraction analysis diagram of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton prepared in Example 2;

[0040] Figure 4 is an X-ray powder diffraction analysis diagram of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton prepared in Example 3;

[0041] Figure 5 is an X-ray powder diffraction analysis diagram of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton prepared in Example 4;

[0042] Figure 6 is the ultraviolet absorption spectrum of the triazolotriazine-based condensed-ring nitrogen-rich organic covalent skeleton prepared in Example 1;

[0043] Figure 7 is a thermogravimetric analysis curve of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton prepared in Example 1;

[0044] Figure 8 This is a diagram showing the efficiency of photocatalytic hydrogen peroxide production of the triazolotriazine-based fused-ring nitrogen-rich organic covalent framework prepared in Example 1.

[0045] Fig. 9 This is a diagram showing the efficiency of photocatalytic reduction of carbon dioxide by the triazolotriazine-based fused-ring nitrogen-rich organic covalent framework prepared in Example 1.

[0046] Fig.10 This is an ultraviolet analysis chart of the photocatalytic reduction of m-nitrophenol by the triazolotriazine-based fused-ring nitrogen-rich organic covalent skeleton prepared in Example 1. DETAILED DESCRIPTION

[0047] The following will describe the embodiments of the present invention with reference to the preferred embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0048] The present invention intends to disclose a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton and a preparation method and application thereof, provide a novel triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton, and thus provide a new photocatalyst.

[0049] The structure of the triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton is shown in Formula I:

[0050]

[0051] Through detection and analysis, it is known that the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton has a C3N4-type organic covalent skeleton with [1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine and triazine ring structure, which breaks the current situation that C3N4-type materials only have two structural units, heptazine and triazine, making it have potential application value in the field of photocatalysts. And the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton of the present invention has a very high nitrogen content. The rich nitrogen element can not only improve the polarity of the material and enhance its interaction with specific substances, but also provide abundant active sites for subsequent modification or functionalization.

[0052] In some embodiments, a method for preparing the above-mentioned triazolotriazine-based fused-ring nitrogen-rich organic covalent framework is also provided, comprising the following steps:

[0053] Adding 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound and catalyst into a reactor, and performing polymerization reaction under heating and inert gas protection to obtain a crude product;

[0054] The crude product is placed in an acid solution or an organic solution and filtered to obtain a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton.

[0055] The preparation method uses 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound as the starting material, and undergoes direct self-polymerization reaction without producing small molecule byproducts, thereby forming a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton with high cross-linking and stability. This structure can resist the influence of various chemical and physical environments, and enhance the durability and service life of the material.

[0056] The above-mentioned preparation method is carried out under the conditions of heating and inert gas protection, avoiding harsh reaction conditions such as high temperature and high pressure, reducing energy consumption and equipment requirements, and improving the safety and feasibility of the preparation process. At the same time, inert gas protection can also effectively prevent the influence of oxygen in the air on the reaction, ensuring the smooth progress of the reaction. The intermediate product is placed in an acid solution for treatment, and a pure nitrogen-rich condensed ring compound can be obtained by a simple filtration operation. This post-treatment method is simple and easy, does not require complex separation and purification steps, and the auxiliary materials used are easy to recycle, reducing production costs and time costs. Because the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton has excellent structural stability and rich nitrogen content, it shows potential application value in many fields. For example, in catalysis, adsorption, separation, energy storage and conversion, the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton can play an important role. In addition, it can also be used as a template or precursor for preparing other materials with special structures and functions, and has broad application prospects.

[0057] Exemplary, the preparation method of triazolotriazine-based condensed ring nitrogen-rich organic covalent framework comprises the following steps:

[0058] Mix 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound and catalyst in a certain proportion in a glove box, and place them in a crucible or ampoule with a ceramic lid. Then seal the crucible or ampoule, and take the sealed crucible or ampoule out of the glove box. If the reaction uses an ampoule as a reactor, the ampoule needs to be vacuum-sealed before starting the reaction. Place the treated crucible or ampoule in a tubular furnace, and vacuum backfill the tubular furnace with inert gas 3 times. Heat the tubular furnace under an inert gas flow, and after the reaction, a crude product of the compound of formula I is obtained.

[0059] The obtained crude product is ground into powder, placed in a solution or an organic solvent, stirred for a period of time, and filtered to obtain a compound of formula I, i.e., a triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton.

[0060] In some embodiments, the catalyst is selected from at least one of trifluoromethanesulfonic acid, trifluoroacetic acid, and potassium chloride-sodium chloride-zinc chloride ternary eutectic salt.

[0061] In some embodiments, the molar ratio of trifluoromethanesulfonic acid or trifluoroacetic acid to 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound is 0.1:1 to 5:1.

[0062] In some embodiments, the mass ratio of potassium chloride-sodium chloride-zinc chloride ternary eutectic salt to 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound is 1:1 to 10:1.

[0063] Exemplarily, the mass ratio of potassium chloride, sodium chloride and zinc chloride is 10:13:75. The ternary eutectic salt is in the form of mixed powder.

[0064] In some embodiments, the heating temperature is 200°C to 350°C.

[0065] In some embodiments, the heating time is 2 to 48 hours.

[0066] In some embodiments, the acid is selected from hydrochloric acid solution, sulfuric acid solution or a mixed solution of the two, and the concentration of the acid in the acid solution is 0.1 to 3.0 mol / L;

[0067] The crude product is placed in an acid solution, stirred for 1 to 24 hours, and then filtered.

[0068] In some embodiments, the organic solvent is an alcohol having 1 to 6 carbon atoms, a nitrile having 1 to 6 carbon atoms, or a mixture of an alcohol and a nitrile.

[0069] In some embodiments, an application of the above-mentioned triazolotriazine-based fused-ring nitrogen-rich organic covalent skeleton is also provided, wherein the triazolotriazine-based fused-ring nitrogen-rich organic covalent skeleton is used as a photocatalyst.

[0070] In some embodiments, the triazolotriazine-based fused-ring nitrogen-rich organic covalent framework is used as a photocatalyst for the preparation of hydrogen peroxide from water, the reduction of CO2 to formic acid, and the reduction of nitrobenzene to aminobenzene.

[0071] Wherein, the structure of 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound is as shown in Formula I:

[0072]

[0073] The above-mentioned nitrogen-rich fused ring compound has the characteristics of a two-dimensional planar structure, rich nitrogen content and three cyano groups, can further undergo cyclotrimerization reaction, and has potential application value in the raw materials of new carbon nitride triazole and triazine-based fused ring nitrogen-rich organic covalent skeletons.

[0074] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the preparation method of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton of the present invention will be further described in detail below in conjunction with specific embodiments and drawings. Obviously, the specific embodiments described are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually merely illustrative and is by no means intended to limit the present application and its applications. Based on the specific embodiments in the present application, all other embodiments obtained by ordinary technicians in the art without paying creative work belong to the scope of protection of the present application.

[0075] If no specific techniques or conditions are specified in the specific embodiments, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0076] Example 1

[0077] A method for preparing a triazolotriazine-based condensed-ring nitrogen-rich organic covalent framework comprises the following steps:

[0078] S1. Grind 1 g of sodium chloride, 1.3 g of potassium chloride and 7.5 g of zinc chloride into a uniform fine mixed powder in a glove box;

[0079] S2, 3 g of the mixed powder prepared in S1 and 1 g of the 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound prepared in Example 1 are mixed evenly in a glove box, and placed in a crucible with a ceramic lid, and then the ceramic lid is tightly closed;

[0080] S3, place the crucible with the ceramic cover in S2 in a tube furnace, and backfill the tube furnace with inert gas for 3 times. Heat the tube furnace to 270°C under an inert gas flow of 10 ml / min, and react for 24 hours. After the reaction is completed, a crude product is obtained;

[0081] S4. Grind the crude product into powder, then pour it into 150 mL of 3 mol / L hydrochloric acid solution, stir it at room temperature for 24 hours, filter it, and wash it with deionized water three times to obtain a triazolotriazine-based fused-ring nitrogen-rich organic covalent skeleton (0.95 g, 95%).

[0082] The reaction equation of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton is as follows:

[0083]

[0084] The structural formula of the triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton is

[0085] Example 2

[0086] A method for preparing a triazolotriazine-based condensed-ring nitrogen-rich organic covalent framework comprises the following steps:

[0087] S1. Grind 1 g of sodium chloride, 1.3 g of potassium chloride and 7.5 g of zinc chloride into a uniform fine mixed powder in a glove box;

[0088] S2, 5 g of the mixed powder prepared in S1 and 1 g of the 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound prepared in Example 1 were mixed evenly in a glove box, and placed in a crucible with a ceramic lid, and then the ceramic lid was tightly closed;

[0089] S3, place the crucible with the ceramic cover in S2 in a tube furnace, and backfill the tube furnace with inert gas for 3 times. Heat the tube furnace to 215°C under an inert gas flow of 10 ml / min, and react for 28 hours. After the reaction is completed, a crude product is obtained;

[0090] S4. Grind the crude product into powder, then pour it into 150 mL of 3 mol / L hydrochloric acid solution, stir it at room temperature for 24 hours, filter it, and wash it with deionized water three times to obtain a triazolotriazine-based fused-ring nitrogen-rich organic covalent skeleton (0.91 g, 91%).

[0091] The reaction equation of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton is as follows:

[0092]

[0093] The structural formula of the triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton is

[0094] Example 3

[0095] A method for preparing a triazolotriazine-based condensed-ring nitrogen-rich organic covalent framework comprises the following steps:

[0096] S1. Add 75 mg of trifluoromethanesulfonic acid and 276 mg of the 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound prepared in Example 1 into an ampoule in a glove box;

[0097] S2, flash freezing the ampoule in S1 with liquid nitrogen in a fume hood, and then vacuum sealing the ampoule in the flash-frozen state to obtain a sealed ampoule with a vacuum state inside and containing the raw material;

[0098] S3. Place the sealed ampoule in S2 into a box furnace and keep it warm at 250°C for 22 hours. Then take out the ampoule, open it in a frozen state, pour the powder inside into 200 mL of methanol, soak it at room temperature for 24 hours, filter it, and wash it with deionized water three times to obtain a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton (0.25 g, 91%).

[0099] The reaction equation of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton is as follows:

[0100]

[0101] The structural formula of the triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton is

[0102] Example 4

[0103] A method for preparing a triazolotriazine-based condensed-ring nitrogen-rich organic covalent framework comprises the following steps:

[0104] S1. Add 57 mg of trifluoroacetic acid and 276 mg of the 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound prepared in Example 1 into an ampoule in a glove box;

[0105] S2, flash freezing the ampoule in S1 with liquid nitrogen in a fume hood, and then vacuum sealing the ampoule in the flash-frozen state to obtain a sealed ampoule with a vacuum state inside and containing the raw material;

[0106] S3. Place the sealed ampoule in S2 into a box furnace and keep it warm at 270°C for 20 hours. Then take out the ampoule, open it in a frozen state, pour the powder inside into 200 mL of methanol, soak it at room temperature for 24 hours, filter it, and wash it with deionized water three times to obtain a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton (0.21 g, 76%).

[0107] The reaction equation of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton is as follows:

[0108]

[0109] The structural formula of the triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton is

[0110] Example 5

[0111] A method for photocatalytically producing hydrogen peroxide using a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton comprises the following steps:

[0112] S1. Add 25 mg of triazolotriazine-based condensed ring nitrogen-rich organic covalent framework to a mixed solution of 45 mL of deionized water and 5 ml of isopropanol, and place the mixture in a 50 mL optical grade quartz bottle reactor. Then, after ultrasonic dispersion of the quartz bottle for 10 min, oxygen is continuously injected into the solution under dark conditions to saturate the solution with oxygen, seal the quartz bottle cap, and stir for 30 min under dark conditions to achieve adsorption-desorption equilibrium.

[0113] S2. Use a filter with λ>400nm to filter the LED light, so that the light passes through the entire bottle from the bottom of the quartz bottle, and a photocatalytic reaction occurs under stirring at 25 degrees Celsius. Then, use a 1ml syringe to take samples every 15 minutes, and use a 0.22μm filter element for solid-liquid separation.

[0114] S3. Use iodine titration to detect the content of hydrogen peroxide in the sample. The specific operation is as follows: add potassium iodide solution (1 ml, 0.4 mol L -1 ), potassium hydrogen phthalate (C8H5KO4) solution (1 ml, 0.1 mol L -1 ), the sample (1 ml) in S2 and deionized water (2 ml) were added to a centrifuge tube, sealed, and stored in a dark environment for 1 hour. The peak intensity at 350 nm was detected using an ultraviolet spectrophotometer, and the photocatalytic hydrogen peroxide production efficiency of the triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton was calculated to be 300 umol g -1 h -1 .

[0115] Example 6

[0116] A method for photocatalytic reduction of carbon dioxide by a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton comprises the following steps:

[0117] S1. Add 50 mg of triazolotriazine-based fused ring nitrogen-rich organic covalent framework to a mixed solution of 30 mL of acetonitrile and 1 ml of triethanolamine, and place the mixture in a 50 mL optical grade quartz bottle reactor. Then, continuously introduce carbon dioxide into the solution in the quartz bottle to remove oxygen from the solution. Seal the quartz bottle cap tightly and stir for 15 minutes in the dark to achieve adsorption-desorption equilibrium.

[0118] S2. Use a 300W xenon lamp as the light source. The light beam is filtered through a filter to visible light of 800nm>λ>400nm. It passes through the entire bottle from the bottom of the quartz bottle and undergoes a photocatalytic reaction under stirring at 25 degrees Celsius. Then, use a 1ml syringe to take samples every 2 hours, and use a 0.22μm filter element for solid-liquid separation. The liquid is the sample to be tested.

[0119] S3. Use an ion chromatograph to detect the concentration of formate in the sample to be tested, wherein the mobile phase is NaHCO3 (1 mM) and Na2CO3 (3.2 mM).

[0120] Finally, according to the data of ion chromatography, the photocatalytic reduction efficiency of CO2 was calculated to be 18.37umol g -1 h -1 .

[0121] Example 7

[0122] A method for photocatalytic reduction of m-nitrophenol to m-aminophenol by a triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton comprises the following steps:

[0123] S1. Add 20 mg of triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton, 30 mg of sodium borohydride and 27.8 mg of m-nitrophenol to a mixed solution of 8 mL of methanol and 12 ml of deionized water, and the mixture is placed in a 25 mL optical grade quartz bottle reactor. The quartz bottle is placed open and stirred for 15 minutes in the dark to reach adsorption-desorption equilibrium. An LED lamp is used as the light source, and the light beam is filtered through a filter to a visible light of 800 nm>λ>400 nm, which passes through the entire bottle from the bottom of the quartz bottle. A photocatalytic reaction occurs under stirring at 25 degrees Celsius. After 1 hour of reaction, a 1 ml syringe is used to take a sample, and a 0.22 μm filter element is used for solid-liquid separation. The liquid is the sample to be tested.

[0124] S2, control group experiment: 30mg sodium borohydride and 27.8mg m-nitrophenol were added to a mixed solution of 8mL methanol and 12ml deionized water, and the mixture was placed in a 25mL optical grade quartz bottle reactor. The quartz bottle was left open and stirred for 15min in the dark to reach adsorption-desorption equilibrium. An LED lamp was used as the light source, and the light beam was filtered through a filter to visible light of 800nm>λ>400nm, which passed through the entire bottle from the bottom of the quartz bottle. A photocatalytic reaction occurred under stirring at 25 degrees Celsius. After 1 hour of reaction, a 1ml syringe was used to take a sample, and a 0.22μm filter was used for solid-liquid separation. The liquid was the sample to be tested.

[0125] S3. Use an ultraviolet spectrophotometer to detect the peak intensity of the sample to be tested in S1 at 400 nm and the peak intensity of the control group S2 at 400 nm, and determine the degree of reduction of the nitro group based on the peak intensity information.

[0126] Detection and analysis:

[0127] 1) The triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton prepared in Example 1 was subjected to nuclear magnetic resonance detection, and the result was as follows: Figure 1 shown.

[0128] The obtained triazolotriazine-based fused-ring nitrogen-rich organic covalent framework was analyzed by solid-state NMR carbon spectroscopy using a BrukerAscend 700M NMR spectrometer.

[0129] from Figure 1 From the analysis, we can see that the carbon spectrum peak is mainly concentrated between the chemical shift of 140 and 170. Since the polymerization process of the monomer is continuous and uncontrollable, the position of the carbon peak is different with the different polymerization amounts, but its basic structure has not changed. It is still a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton cross-linked with triazine. Therefore, although the different carbon peaks are slightly different, they should be concentrated between 140 and 170, which is consistent with the experimental results. This also proves that the polymerization reaction was successfully carried out.

[0130] 2) X-ray diffraction analysis

[0131] The XRD patterns of the triazolotriazine-based fused-ring nitrogen-rich organic covalent skeletons obtained in Examples 1, 2, 3 and 4 were analyzed using Bruker D8 Advance X.

[0132] Figure 2 , Figure 3 , Figure 4 and Figure 5 The XRD spectra of the triazolotriazine-based fused-ring nitrogen-rich organic covalent skeletons obtained in Example 1, Example 2, Example 3 and Example 4 are respectively.

[0133] from Figure 2 , Figure 3 , Figure 4 and Figure 5 From the analysis, it can be seen that the four samples obtained have similar XRD patterns, among which the low-angle peak at 11° corresponds to the cavity in the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton, and the high-angle peak at 27° corresponds to the peak of interlayer π-π stacking.

[0134] 3) UV analysis

[0135] The triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton obtained in Example 1 was tested for ultraviolet-visible light absorption using a Shimadzu UV3600 ultraviolet / visible / near-infrared diffuse reflectometer. The results are as follows: Figure 6 shown.

[0136] from Figure 6 It can be seen that the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton has light absorption in the visible light range of 400-650nm, which proves that the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton can be used as a visible light absorber to catalyze the production of hydrogen peroxide.

[0137] 4) Thermogravimetric analysis

[0138] The triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton prepared in Example 1 was subjected to thermogravimetric analysis.

[0139] The specific operation is: take 5 mg of sample in an alumina crucible and heat it from 30°C to 800°C at a heating rate of 10°C per minute to explore the thermal stability of the sample. The results are as follows Figure 7 shown.

[0140] from Figure 7 It can be seen that the weight loss peak at 100°C corresponds to the weight loss of water adsorbed by the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton, and the weight loss at 350°C corresponds to the beginning of decomposition of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton. This shows that the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton has high thermal stability and its decomposition temperature is as high as 350°C.

[0141] 5) Photocatalytic analysis

[0142] The photocatalytic hydrogen peroxide production experiment was carried out using a triazolotriazine-based fused-ring nitrogen-rich organic covalent framework as a catalyst.

[0143] The specific operation is as follows: 25 mg of the triazolotriazine-based fused ring nitrogen-rich organic covalent skeleton prepared in Example 1, 45 ml of deionized water, and 5 ml of isopropanol are added to a 50 ml photoreactor, and the mixture is illuminated for 1 hour under stirring. 1 ml of the reaction solution is taken every 15 minutes, and the concentration of hydrogen peroxide in 1 ml of the reaction solution is measured by iodine titration, and the concentration of hydrogen peroxide in the photoreactor is calculated based on the result. Figure 8 shown.

[0144] from Figure 8 The metal-free triazolotriazine-based condensed ring nitrogen-rich organic covalent framework has the ability to photocatalytically produce hydrogen peroxide with a catalytic efficiency of 300 umol g -1 h -1 .

[0145] Experiments on photocatalytic reduction of carbon dioxide were carried out using triazolotriazine-based fused-ring nitrogen-rich organic covalent framework as catalyst.

[0146] The specific operation is as follows: 50 mg of the triazolotriazine-based fused ring nitrogen-rich organic covalent framework prepared in Example 1, 30 mL of acetonitrile and 1 ml of triethanolamine are added to a 50 mL optical grade quartz bottle reactor. The reaction mixture is stirred at 25°C for 10 hours, and 1 ml of the reaction solution is taken every 2 hours. The formate ion concentration in the reaction solution is detected using an ion chromatograph. The results are as follows. Fig. 9 shown.

[0147] According to the ion chromatography data, Fig. 9The metal-free triazolotriazine-based fused-ring nitrogen-rich organic covalent framework has the potential to photocatalytically reduce CO2 to HCOO. - The photocatalytic reduction efficiency of CO2 is 18.37umol g -1 h -1 .

[0148] The triazolotriazine-based fused-ring nitrogen-rich organic covalent skeleton prepared in Example 1 was used as a catalyst to carry out a photocatalytic reduction experiment of m-nitrophenol.

[0149] The specific operation is as follows: Take 20 mg of triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton, 30 mg of sodium borohydride and 27.8 mg of m-nitrophenol, add to a mixed solution of 8 mL of methanol and 12 ml of deionized water, and transfer the mixed solution to a 25 ml optical grade quartz bottle reactor. React for 1 hour at 25°C with stirring. In the control group experiment, except that the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton was not added, the rest of the operations were the same. After 1 hour of reaction, use an ultraviolet spectrophotometer to detect the ultraviolet absorption of the solution, where 400 nm represents the nitro peak intensity. The results are as follows Fig.10 shown.

[0150] from Fig.10 From the analysis, it can be seen that in the control group experiment, due to the absence of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton, an obvious ultraviolet peak appeared at 400nm, indicating that there were still sufficient nitro groups in the solution. After adding the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton, it can be seen that the ultraviolet peak at 400nm almost disappeared after 1 hour of illumination, indicating that the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton effectively reduced the nitro group in m-nitrophenol to amino group.

[0151] In summary, the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton of the present invention has a C3N4-type organic covalent skeleton with [1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine and triazine ring structures, which breaks the current situation in which C3N4-type materials have only two structural units, heptazine and triazine, making it have potential application value in the field of photocatalysts. And the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton of the present invention has a very high nitrogen content. The rich nitrogen element can not only increase the polarity of the material and enhance its interaction with specific substances, but also provide abundant active sites for subsequent modification or functionalization.

[0152] The preparation method of the present invention generally uses 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound as a starting material, undergoes a self-polymerization reaction, and does not produce small molecular byproducts in the process, thereby forming a triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton with high cross-linking and stability. This structure can resist the influence of various chemical and physical environments, and enhance the durability and service life of the material.

[0153] The preparation method of the present invention is carried out under the conditions of heating and inert gas protection, avoiding harsh reaction conditions such as high temperature and high pressure, reducing energy consumption and equipment requirements, and improving the safety and feasibility of the preparation process. At the same time, inert gas protection can also effectively prevent the influence of oxygen in the air on the reaction, ensuring the smooth progress of the reaction. The intermediate product is placed in an acid solution for treatment, and a pure nitrogen-rich condensed ring compound can be obtained by a simple filtering operation. This post-processing method is simple and easy, without complex separation and purification steps, reducing production costs and time costs. Since the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton has excellent structural stability and rich nitrogen content, it shows potential application value in multiple fields. For example, in catalysis, adsorption, separation, energy storage and conversion, etc., the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton can play an important role. In addition, it can also be used as a template or precursor for preparing other materials with special structures and functions, has broad application prospects, and has promotion and application value in the field of organic compound technology.

[0154] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent substitution or change made by a person skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A triazolotriazine-based condensed ring nitrogen-rich organic covalent framework, characterized in that: The structure of the nitrogen-rich fused ring compound is shown in Formula I:

2. A method for preparing the triazolotriazine-based condensed-ring nitrogen-rich organic covalent framework as claimed in claim 1, characterized in that: The following steps are involved: Adding 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound and catalyst into a reactor, and performing polymerization reaction under heating and inert gas protection to obtain a crude product; The crude product is placed in an acid solution or an organic solvent and filtered to obtain the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton.

3. The method for preparing the triazolotriazine-based condensed-ring nitrogen-rich organic covalent framework according to claim 2, characterized in that: The catalyst is selected from at least one of trifluoromethanesulfonic acid, trifluoroacetic acid and potassium chloride-sodium chloride-zinc chloride ternary eutectic salt.

4. The method for preparing the triazolotriazine-based condensed-ring nitrogen-rich organic covalent framework according to claim 3, characterized in that: The molar ratio of the trifluoromethanesulfonic acid or trifluoroacetic acid to the 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound is 0.1:1 to 5:

1.

5. The method for preparing the triazolotriazine-based condensed-ring nitrogen-rich organic covalent framework according to claim 3, characterized in that: The mass ratio of the potassium chloride-sodium chloride-zinc chloride ternary eutectic salt to the 2,6,10-tricarbonitrile-tris[1,2,4]triazolo[1,5-a:1',5'-c:1",5"-e][1,3,5]triazine compound is 1:1 to 10:

1.

6. The method for preparing the triazolotriazine-based condensed-ring nitrogen-rich organic covalent framework according to claim 2, characterized in that: The heating temperature is 200°C to 350°C; And / or, the heating time is 2 to 48 hours.

7. The method for preparing the triazolotriazine-based condensed-ring nitrogen-rich organic covalent framework according to claim 2, characterized in that: The acid solution is selected from hydrochloric acid solution, sulfuric acid solution or a mixed solution of the two, and the concentration of the acid in the acid solution is 0.1-3.0 mol / L; The crude product is placed in an acid solution, stirred for 1 to 24 hours, and then filtered.

8. The method for preparing the triazolotriazine-based condensed-ring nitrogen-rich organic covalent framework according to claim 2, characterized in that: The organic solvent is an alcohol with 1 to 6 carbon atoms, a nitrile with 1 to 6 carbon atoms, or a mixture of an alcohol and a nitrile.

9. An application of the triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton as claimed in claim 1, characterized in that: The triazolotriazine-based fused-ring nitrogen-rich organic covalent framework acts as a photocatalyst.

10. The use according to claim 9, characterized in that: Application of the triazolotriazine-based condensed ring nitrogen-rich organic covalent framework as a photocatalyst for preparing hydrogen peroxide from water; Application of the triazolotriazine-based fused-ring nitrogen-rich organic covalent framework as a photocatalyst for the reduction of CO2 to formic acid; The triazolotriazine-based condensed ring nitrogen-rich organic covalent skeleton is used as a photocatalyst for reducing m-nitrophenol to m-aminophenol.

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