A two-dimensional covalent organic framework material based on tricyclic quinazoline monomers, and a preparation method and application thereof

Abstract

This application proposes a two-dimensional covalent organic framework (COF) based on a tricyclic quinazoline monomer, its preparation method, and its applications. The COF has the structural unit shown in Formula I. The planar rigid tricyclic quinazoline is covalently linked by imine, phenyl, and / or triazine, exhibiting a highly delocalized, highly conjugated system. This forms a highly crystalline and highly conjugated COF with a regular 2D layered structure and 1D π-π stacked columnar channels. The COF can efficiently photocatalyze hydrogen evolution without additional co-catalysts, and its hydrogen evolution rate exceeds that of many previously reported platinum-modified COFs, metal-containing inorganic photocatalysts, and their composites. The COF is prepared by reacting a tricyclic quinazoline-functionalized amino-protecting monomer with trialdehyde-phenyltriazine or trialdehyde-phenylbenzene under solvothermal conditions via a Schiff base reaction. The preparation method is mature, simple, and capable of large-scale preparation.

Description

Technical Field

[0001] This application belongs to the field of covalent organic framework materials technology, and particularly relates to a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer, its preparation method and application. Background Technology

[0002] Currently, the world's energy mainly relies on non-renewable fossil resources, and its energy structure faces the dual pressures of economic development and environmental protection. Environmental problems such as the greenhouse effect and air pollution continue to emerge, making the transformation of energy production and consumption patterns towards cleaner and lower-carbon energy imperative. Hydrogen energy has advantages such as high energy density and zero carbon emissions, and abundant raw materials, making it an ideal clean secondary energy source. Although my country is the world's largest hydrogen producer, most of it still comes from fossil fuels (i.e., "grey hydrogen"). The fundamental principle of "clean and low-carbon" hydrogen production is to develop renewable energy sources. Among these, solar energy resources are abundant, widely distributed, economical, and environmentally friendly; therefore, photocatalytic water splitting for hydrogen production is an important pathway to achieve efficient conversion of solar energy into chemical energy, but it is highly dependent on semiconductors that can widely utilize visible light. Among them, inorganic semiconductors containing metals (such as metal oxides, nitrides, halides, and sulfides) mostly suffer from problems such as untunable structure, weak visible light absorption, wide band gap, rapid charge carrier recombination, and photocorrosion. In contrast, organic semiconductors, especially covalent organic frameworks (COFs), have the characteristics of diverse and tunable structure, strong light absorption, tunable band gap, large specific surface area, and easy functionalization modification, and have become promising alternative materials for photodriven catalytic hydrogen evolution.

[0003] However, many organic polymers and COFs lack inherent water-splitting activity and still require metal cocatalysts (especially platinum) to improve photocatalytic reaction kinetics. This dependence on metal active centers limits the sustainable development and large-scale application of material systems. A major limitation of metal-based cocatalysts is the energy loss at the photocatalyst-cocatalyst interface caused by lattice or energy mismatch. This mismatch hinders interfacial charge separation, which is a key factor in solar energy conversion efficiency. Despite significant efforts to improve interfacial charge separation, effective solutions remain limited.

[0004] Completely eliminating the co-catalyst requires the photocatalyst itself to contain effective catalytic active sites. Although progress has been made in hydrogen production by modulating the DA structure and introducing active groups, or by embedding metal coordination catalytic structures into COFs, developing photocatalysts capable of achieving efficient water splitting without metal co-catalysts remains a significant challenge. Summary of the Invention

[0005] For the reasons stated above, one objective of this invention is to provide a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer, comprising a tricyclic quinazoline and triphenylbenzene or triphenyltriazine; the tricyclic quinazoline unit has a planar disk-like rigid structure and C 3h Symmetry, including highly delocalized large conjugated systems; COFs have regular 2D layered structures and 1D π-π stacked columnar channels, in which the nitrogen atoms in the three outer C=N structures are exposed at the edge of the molecular skeleton, have high Lewis basicity, and serve as ideal proton anchoring sites, which can rapidly adsorb protons in solution and achieve photocatalytic hydrogen evolution without additional co-catalysts.

[0006] The second objective of this invention is to provide a method for preparing two-dimensional covalent organic framework materials based on tricyclic quinazoline monomers. The method involves reacting a tricyclic quinazoline-functionalized amino protecting monomer with trialdehyde phenyltriazine or trialdehyde phenylbenzene under solvothermal conditions to form a highly crystalline and highly conjugated two-dimensional covalent organic framework material. The preparation method is mature, the process is simple, and it can be used to prepare COFs on a large scale.

[0007] The third objective of this invention is to provide a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer as a photocatalytic hydrogen production catalyst for water. It can effectively produce hydrogen from water without the need for additional co-catalysts, and the hydrogen evolution rate exceeds that of many reported platinum-modified COFs, metal-containing inorganic photocatalysts and their composite materials.

[0008] The first objective of this invention can be achieved by adopting the following technical solution:

[0009] A two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer has the structural unit shown in formula (I):

[0010] ;

[0011] Among them, X1 is simultaneously C or N; X2 is simultaneously C or N; X3 is simultaneously C or N.

[0012] The second objective of this invention can be achieved by adopting the following technical solution:

[0013] A method for preparing a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer involves reacting a monomer with the structure shown in Formula II and a monomer with the structure shown in Formula III under solvothermal conditions using a Schiff base reaction to obtain the two-dimensional covalent organic framework material based on the tricyclic quinazoline monomer.

[0014] ;

[0015] In the structural monomer shown in Equation III, X can be either C or N.

[0016] Furthermore, the molar ratio of the monomers in the structure shown in Formula II to the monomers in the structure shown in Formula III is 1:(0.9-1.2).

[0017] Furthermore, the solvent for the solvothermal reaction is mesitylene and / or 1,4-dioxane;

[0018] The molar volume ratio of the monomer and solvent in the structure shown in Formula II is (10-80) μmol: 1 mL.

[0019] Furthermore, the reaction is carried out in the presence of acetic acid, with the concentration of acetic acid being 5-7 mol / L and the amount of acetic acid added being 5%-15% of the solvent volume.

[0020] Furthermore, the reaction conditions are: reacting at 100-140℃ for 12-120h.

[0021] Furthermore, the monomer with the structure shown in Formula II is prepared by the following method: ;

[0022] Furthermore, the reaction conditions were as follows: tris(dibenzylideneacetone)dipalladium was used as a catalyst, 1,1'-binaphthyl-2,2'-bis(diphenylphosphine) was used as the catalyst organic ligand, toluene was used as the solvent, and sodium tert-butoxide was used as the base, and the reaction was carried out at 100-130℃.

[0023] The third objective of this invention can be achieved by adopting the following technical solution:

[0024] Application of two-dimensional covalent organic framework materials based on tricyclic quinazoline monomers as photocatalytic catalysts for hydrogen production from water.

[0025] Furthermore, the photocatalytic hydrogen production system consists of a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer as the catalyst, ruthenium terpyridine as the photosensitizer, triethylamine as the electron sacrificial agent, acetonitrile and water as the solvent, and LED white light as the light source.

[0026] The advantages or beneficial effects of the above technical solutions include at least the following:

[0027] In the two-dimensional covalent organic framework material based on tricyclic quinazoline monomers of the present invention, the planar rigid tricyclic quinazoline is covalently linked by imine, phenyl and / or triazine, resulting in a highly delocalized, highly conjugated system. This allows for the formation of highly crystalline, highly conjugated COFs with a regular 2D layered structure and 1D π-π stacked columnar channels. On one hand, the imine promotes charge separation, with photogenerated electrons migrating to the nitrogen atom of the imine. On the other hand, the nitrogen atom in the peripheral imine structure can rapidly adsorb protons from the solution. Thus, the high nitrogen activity directly serves as the intrinsic catalytic site, achieving photocatalytic hydrogen evolution without additional co-catalysts. The hydrogen evolution rate exceeds that of many previously reported platinum-modified COFs, metal-containing inorganic photocatalysts, and their composite materials.

[0028] The present invention provides a method for preparing two-dimensional covalent organic framework materials based on tricyclic quinazoline monomers. This method utilizes a Schiff base reaction between a tricyclic quinazoline-functionalized amino protecting monomer and a trialdehyde phenyltriazine or trialdehyde phenylbenzene under solvothermal conditions to form a highly crystalline and highly conjugated two-dimensional covalent organic framework material. The preparation method is mature and the process is simple, enabling large-scale preparation of COFs.

[0029] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of this application will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0031] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0032] Figure 1 The proton NMR spectrum of TCQ-3 (N=CPh2) prepared in Example 2;

[0033] Figure 2 The carbon NMR spectrum of TCQ-3 (N=CPh2) prepared in Example 2;

[0034] Figure 3 C-13 magic angle rotation NMR images of TCQ-PT-COF prepared in Example 3 and TCQ-PB-COF prepared in Example 4;

[0035] Figure 4 X-ray powder diffraction pattern of TCQ-PT-COF prepared in Example 3;

[0036] Figure 5X-ray powder diffraction pattern of TCQ-PB-COF prepared in Example 4;

[0037] Figure 6 This is a schematic diagram of the AA stacked simulated structure of TCQ-PT-COF prepared in Example 3;

[0038] Figure 7 This is a schematic diagram of the AA stacked simulated structure of TCQ-PB-COF prepared in Example 3;

[0039] Figure 8 Fourier transform infrared spectra of TCQ-PT-COF prepared in Example 3 and TCQ-PB-COF prepared in Example 4;

[0040] Figure 9 The graph shows the photocatalytic hydrogen evolution yield of TCQ-PT-COF and TCQ-PB-COF under different conditions;

[0041] Figure 10 Figures showing the hydrogen evolution yield under different catalysts;

[0042] Figure 11 The graph shows the hydrogen evolution yield of five rounds of photocatalytic oxidation using TCQ-PT-COF.

[0043] Figure 12 This is a structural unit diagram of a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer. Detailed Implementation

[0044] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this application. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0045] Many COFs lack intrinsic activity for water splitting and reduction, and must rely on (noble) metal-based cocatalysts to improve photocatalytic reaction kinetics. Existing photocatalytic hydrogen production technologies' dependence on metal (especially noble metals such as platinum) cocatalysts significantly increases material costs, and the scarcity of noble metal reserves severely limits their use. Furthermore, a major limitation of metal-based cocatalysts is the energy loss at the photocatalyst-cocatalyst interface caused by lattice or energy mismatch, which severely hinders the separation of interfacial charges. This significantly affects the solar-to-chemical energy conversion efficiency, thus limiting the large-scale expansion of photocatalytic hydrogen production technology. In view of this, this application provides a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer, its preparation method, and its applications.

[0046] A two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer has the structural unit shown in formula (I). Figure 12 ):

[0047] ;

[0048] Among them, X1 is simultaneously C or N; X2 is simultaneously C or N; X3 is simultaneously C or N.

[0049] Tricyclic quinazoline has a planar, disk-like rigid structure and C 3h Symmetry, including highly delocalized large conjugated systems. After assembly into COFs, this planar configuration readily forms tight interlayer π-π stacking, providing an efficient channel for ultrafast interlayer migration of charge carriers along directions perpendicular to the planar surface. The symmetry of the molecule masks its strong internal electronic asymmetry. The central nitrogen atom (with lone pairs participating in the π-conjugation system) exhibits an electron-donating tendency; while the three peripheral imine nitrogen atoms (with lone pairs located in the molecular plane and not participating in π-conjugation) exhibit a strong electron-withdrawing tendency due to their higher electronegativity. This intrinsic "push-pull" electron distribution leads to strong internal polarization of the molecule, forming multiple polar resonances. This causes a directional shift in charge density within the framework, providing an intrinsic driving force for the separation of excited electrons; after COFs absorb photons and generate excitons, the polar resonance structure within the molecule drives electrons to migrate rapidly to the electron-withdrawing nitrogen atoms at the edges, while holes remain in the framework or central region. Traditional photocatalysts typically require noble metals (such as Pt) as co-catalysts to enrich electrons and provide reaction sites. The nitrogen atoms in the three outer C=N structures have their unconjugated lone pairs of electrons fully exposed at the edge of the molecular skeleton. The high electronegativity of these exposed lone pairs endows these three edge nitrogen atoms with high Lewis basicity; they are ideal proton anchoring sites and highly active catalytic sites.

[0050] In this embodiment, when X1, X2, and X3 are all C, the linking structure is phenyl; when X1, X2, and X3 are all N, the linking structure is triazine; when X1, X2, and X3 are N or C, but not completely different, the linking structure is a mixture of benzene and triazine.

[0051] This invention provides a method for preparing a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer. The two-dimensional covalent organic framework material based on the tricyclic quinazoline monomer is prepared by reacting the monomer with the monomer with the structure shown in Formula II and the monomer with the structure shown in Formula III under solvothermal conditions through a Schiff base reaction. ;

[0052] In the structural monomer shown in Equation III, X can be either C or N.

[0053] In the monomer of Formula II, the tricyclic quinazoline has three amino groups, protected by amino protecting groups; the monomer of Formula III has three aldehyde groups. Therefore, the monomers of Formula II and Formula III undergo a Schiff base reaction under solvothermal conditions to form a highly crystalline, highly conjugated two-dimensional covalent organic framework material. In this embodiment,

[0054] In one embodiment, the molar ratio of the monomers in the structure shown in Formula II to the monomers in the structure shown in Formula III is any point value or any two points within the range of 1:(0.9-1.2). For example, the molar ratios are 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.1, 1:1.15, 1:1.2, etc.

[0055] In one embodiment, the solvent for the solvothermal reaction is mesitylene and / or 1,4-dioxane. In this embodiment, when the solvent is a mixture of mesitylene and 1,4-dioxane, the volume ratio of mesitylene to 1,4-dioxane is any value between 1:(0.1-10) or any two values ​​within a range. Preferably, the volume ratio of mesitylene to 1,4-dioxane is 1:1.

[0056] In one embodiment, the molar-to-volume ratio of the monomer and solvent in the structure shown in Formula II is any value between (10-80) μmol:1 mL or any two values ​​within a range. Examples of molar-to-volume ratios include 10 μmol:1 mL, 20 μmol:1 mL, 30 μmol:1 mL, 40 μmol:1 mL, 50 μmol:1 mL, 60 μmol:1 mL, 70 μmol:1 mL, 80 μmol:1 mL, etc.

[0057] In one embodiment, the reaction is carried out in the presence of acetic acid, with the concentration of acetic acid being 5-7 mol / L, and the amount of acetic acid added being any point value or any two points within the range of 5%-15% of the solvent volume. For example, the amount of acetic acid added is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% of the solvent volume, etc.

[0058] In one implementation method, the reaction conditions are: reacting at 100-140°C for 12-120 hours. The reaction temperature can be any point or any two points within the range of 100-140°C. For example, the reaction temperature can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, etc.; the reaction time can be any point or any two points within the range of 12-120 hours. For example, the reaction time can be 12 hours, 24 hours, 36 hours, 48 ​​hours, 60 hours, 72 hours, 84 hours, 96 hours, 108 hours, 120 hours, etc.

[0059] In one implementation method, the reaction is carried out in a glass tube. After the material is added to the glass tube, the glass tube is sealed with an oxyhydrogen flame and then heated.

[0060] As one implementation method, the reaction also includes solid-liquid separation and a purification process for the solid:

[0061] Purification includes washing and / or Soxhlet extraction; the solvent used for washing is DMF and / or dichloromethane; the solvent used for Soxhlet extraction is tetrahydrofuran.

[0062] As one implementation method, after solid-liquid separation, the solid sample is washed with DMF (5 mL × 5) and dichloromethane (5 mL × 5), then Soxhlet extracted in THF solution for 1-5 days, and vacuum dried to obtain a two-dimensional covalent organic framework material based on tricyclic quinazoline.

[0063] As one embodiment, the monomer with the structure shown in Formula II is prepared by the following method:

[0064] ;

[0065] In this application, 2,7,12-tribromotricyclic quinazoline is coupled with benzophenone imine to prepare a tricyclic quinazoline monomer with an amino protecting group as shown in Formula II; wherein the imine group is located at 2,7,12 and can act as a group that reacts with the aldehyde group, and is reacted with a monomer with three aldehyde groups as shown in Formula III to prepare a cyclic structural unit, thereby obtaining COFs.

[0066] As one embodiment, the reaction conditions are as follows: tris(dibenzylacetone)dipalladium is used as a catalyst, 1,1'-binaphthyl-2,2'-bis(diphenylphosphine) is used as the catalyst organic ligand, toluene is used as the solvent, sodium tert-butoxide is used as the base, and the reaction is carried out at 100-130°C.

[0067] As one embodiment, 2,7,12-tribromotricyclic quinazoline was prepared by reacting 6-bromobenzo[C]isoxazole with ammonium acetate.

[0068] ;

[0069] In one embodiment, the reaction is carried out in a sulfolane solvent at a temperature of 130-160°C for 8-24 hours.

[0070] This invention also provides an application of a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer as a photocatalytic catalyst for hydrogen production from water.

[0071] In one implementation method, the photocatalytic hydrogen production system comprises: a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer as the catalyst, ruthenium terpyridine as the photosensitizer, triethylamine as the electron sacrificial agent, acetonitrile and water as the solvent, and white LED light as the light source. Using the two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer of this invention as the catalyst, the photocatalytic system requires no other co-catalyst.

[0072] The following is a further explanation using specific embodiments.

[0073] Example 1

[0074]

[0075] 2 mmol of 6-dibromobenzene[c]isoxazole and 4 mmol of ammonium acetate were mixed evenly in 5 mL of sulfolane solvent and reacted at 150 °C for 16 h to produce a precipitate. The precipitate was filtered, washed with ethanol, and dried to obtain 2,7,12-tribromotricycloquinazoline.

[0076] Example 2

[0077] ;

[0078] Under a nitrogen atmosphere, 1.6 mmol of tris(dibenzylacetone)dipalladium and 2.1 mmol of 1,1'-binaphthyl-2,2'-bis(diphenylphosphine) were dissolved in 200 mL of toluene and reacted at 110 °C for 30 min. The mixture was then cooled to room temperature, and 10 mmol of 2,7,12-tribromotricyclic quinazoline, 300 mmol of sodium tert-butoxide, and 43.2 mmol of benzophenone imine were added. The reaction was continued at 110 °C for 12 h. After the reaction, column chromatography yielded the amino-protected tricyclic quinazoline monomer of Formula II, named TCQ-3 (N=CPh2). The 1H NMR spectrum is shown below. Figure 1 As shown, the carbon NMR spectrum is as follows: Figure 2 As shown.

[0079] The proton NMR data are as follows:

[0080] 1H NMR (400MHz, Chloroform-d) δ7.77(s, 1H), 7.69(dJ=7.4Hz, 2H), 7.39(d, J=7.1Hz, 1H), 7.34(d, J=7.6H z, 2H), 7.19 (d, J=4.4Hz, 3H), 7.09 (d, J=7.9Hz, 3H), 6.74 (d, J=8.5Hz, 1H); The carbon NMR data are as follows:

[0081] 13 C NMR (100MHz, CDCl3) δ169.20, 150.03, 144.37, 140.83, 139.49, 136.01, 131.09, 129.67, 12 9.56, 128.99, 128.37, 128.25, 127.31, 127.18, 121.50, 117.49, 77.16.

[0082] Example 3

[0083] 25.6 μmol of a tricyclic quinazoline monomer with an amino-protected group (SEM) of Formula II and 25.6 μmol of a trialdehyde phenyl triazine monomer (SEM) of Formula III were weighed into a glass tube (8 × 150 mm). 600 μL of mesitylene, 600 μL of 1,4-dioxane, and 160 μL of 6M acetic acid solution were added. The mixture was then sonicated for 10 min. The glass tube was sealed with an oxyhydrogen flame and heated in an oven at 120 °C for 72 h, then allowed to cool naturally to room temperature. The powder was collected by filtration, washed with DMF (5 mL × 5) and dichloromethane (5 mL × 5), then Soxhlet extracted in tetrahydrofuran for 3 days, and dried under vacuum to obtain a two-dimensional covalent organic framework material based on the tricyclic quinazoline monomer, named TCQ-PT-COF. C-13 magic angle rotation NMR was observed as follows: Figure 3 As shown.

[0084] Example 4

[0085] 25.6 μmol of a tricyclic quinazoline monomer with an amino-protected group (SEM) of Formula II and 25.6 μmol of a trialdehyde phenylbenzene (SEM) of Formula III were weighed into a glass tube (8 × 150 mm). 600 μL of mesitylene, 600 μL of 1,4-dioxane, and 160 μL of 6M acetic acid solution were added. The mixture was then sonicated for 10 min. The glass tube was sealed with an oxyhydrogen flame and heated in an oven at 120 °C for 72 h, then allowed to cool naturally to room temperature. The powder was collected by filtration, washed with DMF (5 mL × 5) and dichloromethane (5 mL × 5), then Soxhlet extracted in tetrahydrofuran for 3 days, and dried under vacuum to obtain a two-dimensional covalent organic framework material based on the tricyclic quinazoline monomer, named TCQ-PB-COF. C-13 magic angle rotation NMR was observed as follows: Figure 3 As shown.

[0086] Example 5

[0087] Weigh 25.6 μmol of the tricyclic quinazoline monomer with an amino-protected group (Symbol. II) and 23.04 μmol of the trialdehyde phenyl triazine monomer (Symbol. III) into a glass tube (8 × 150 mm). Add 320 μL of 1,4-dioxane and 48 μL of 6M acetic acid solution. Then sonicate the mixture for 10 min. Seal the glass tube with an oxyhydrogen flame and heat it in an oven at 100 °C for 120 h. Then cool it naturally to room temperature. Filter and collect the powder. Wash the powder sample with DMF (5 mL × 5) and dichloromethane (5 mL × 5). Then extract it in tetrahydrofuran for 3 days and dry it in vacuum to obtain a two-dimensional covalent organic framework material based on the tricyclic quinazoline monomer, named TCQ-PT-COF.

[0088] Example 6

[0089] Weigh 25.6 μmol of the tricyclic quinazoline monomer with an amino-protected group (Symbol. II) and 30.72 μmol of the trialdehyde phenylbenzene (Symbol. III) into a glass tube (8 × 150 mm). Add 2.56 mL of mesitylene and 128 μL of 6M acetic acid solution. Then sonicate the mixture for 10 min. Seal the glass tube with an oxyhydrogen flame and heat it in an oven at 140 °C for 12 h. Then cool it naturally to room temperature. Filter and collect the powder. Wash the powder sample with DMF (5 mL × 5) and dichloromethane (5 mL × 5). Then extract it in tetrahydrofuran by Soxhlet for 3 days and dry it in vacuum to obtain a two-dimensional covalent organic framework material based on the tricyclic quinazoline monomer, named TCQ-PB-COF.

[0090] Materials testing:

[0091] (1) X-ray powder diffraction tests were performed on TCQ-PT-COF prepared in Example 3 and TCQ-PB-COF prepared in Example 4. The X-ray powder diffraction of TCQ-PT-COF is as follows: Figure 4 As shown; X-ray powder diffraction of TCQ-PB-COF is as follows: Figure 5 As shown.

[0092] The X-ray powder diffraction results show that the diffraction patterns of the synthesized TCQ-PT-COF and TCQ-PB-COF are highly consistent with the X-ray powder diffraction of the AA stacked structure simulated by Materials Studio software in terms of peak position, indicating that the synthesized COFs are two-dimensional layered structures of AA stacking. Moreover, the diffraction patterns also show that the diffraction peaks of the COFs are very strong and sharp, indicating that the synthesized covalent organic framework materials have high crystallinity.

[0093] The AA stacking simulation structure of TCQ-PT-COF is as follows: Figure 6 As shown, the AA stacking simulation structure of TCQ-PB-COF is as follows: Figure 7 As shown.

[0094] (2) Fourier transform infrared spectroscopy was performed on the TCQ-PT-COF prepared in Example 3 and the TCQ-PB-COF prepared in Example 4. The infrared spectra are shown below. Figure 8 As shown.

[0095] from Figure 8 Infrared spectroscopy reveals that after the monomer is synthesized into COF, the wavelengths at 2680-2860 and 1700 cm⁻¹ are... -1 The peaks representing the stretching vibrations of the aldehyde group CH and C=O are weakened at 700 cm⁻¹. -1 The benzene ring CH bending vibration peak, representing the TCQ amino protecting group, is weakened, and the peak at 1630 cm⁻¹ is also reduced. -1 The peak at this point represents the newly formed C=N stretching vibration of the imine bond, which indicates the reaction of amine-aldehyde condensation.

[0096] Experimental example:

[0097] The photocatalytic hydrogen evolution performance of TCQ-PT-COF prepared in Example 3 and TCQ-PB-COF prepared in Example 4 was tested. The system used COF as catalyst, ruthenium terpyridine (Ru(bpy)3Cl2) as photosensitizer, triethylamine (TEA) as electron sacrificial agent, acetonitrile (MeCN) and water as solvent, and LED white light as light source. The catalytic time was 1 h. The amount of hydrogen was determined by gas chromatography.

[0098] (1) Under the conditions of H2O, MeCN+H2O, MeCN+H2O+Ru(bpy)3Cl2, MeCN+H2O+TEA, H2O+Ru(bpy)3Cl2+TEA, and MeCN+H2O+TEA+Ru(bpy)3Cl2, respectively, TCQ-PT-COF was used as the catalyst, LED white light was used as the light source, and the catalytic time was 1 h. The hydrogen production rate was measured and calculated. The results are as follows: Figure 9 As shown.

[0099] Figure 9 The results of the control experiments show that COF and triethylamine are indispensable for the photocatalytic system of this invention, and COF also exhibits certain performance (1.53 mmol g⁻¹ h⁻¹) even without a photosensitizer. -1 However, the performance was improved by nearly 30 times with the addition of a photosensitizer. Furthermore, COF also exhibits certain performance in pure water systems (5.5 mmol g). -1 h -1 ).

[0100] (2) Under optimal conditions (2.5 mg catalyst, 12.5 mg Ru(bpy)3Cl2·6H2O, 1.5 mL TEA, 3.5 mL MeCN, 1 mL H2O), TCQ-PT-COF, TCQ-PB-COF, monomers with the structure shown in Formula II (TCQ-3(N=CPh2)), tricyclic quinazoline (TCQ), trialdehyde phenyltriazine (TFPT), and trialdehyde phenylbenzene (TFPB) were used as catalysts, with LED white light as the light source, and a catalytic time of 1 h. A control experiment was conducted to determine the hydrogen production. The results are as follows: Figure 10 As shown.

[0101] The amino-protected TCQ monomer (TCQ-3(N=CPh2)) has similar properties to TCQ-PB-COF, while the unmodified TCQ monomer also has some properties, and other aldehyde monomers have no properties.

[0102] Under optimal conditions, TCQ-PT-COF exhibited a concentration of 45.44 mmol / g. -1 h -1 The hydrogen evolution rate of TCQ-PB-COF was 30.49 mmol g. -1 h -1 The hydrogen evolution rate.

[0103] (3) The TCQ-PT-COF was subjected to five rounds of catalytic reaction under optimal conditions (1 hour each time, for a total of 5 hours). The hydrogen evolution rate in each round of reaction was measured, and the results are as follows: Figure 11 As shown.

[0104] In the five rounds of catalytic reaction, the hydrogen production rate remained basically unchanged after increasing, showing a stable and efficient hydrogen production rate, indicating that the catalyst structure and performance are stable.

[0105] In summary, this application provides two two-dimensional covalent organic framework materials based on tricyclic quinazoline, which can serve as highly efficient photocatalysts to effectively generate hydrogen from water without the need for additional cocatalysts. Without additional cocatalysts, the photocatalytic hydrogen evolution rates of TCQ-PT-COF and TCQ-PB-COF can reach 45.44 mmol g, respectively. -1 h -1 and 30.5 mmol g -1 h -1 It surpasses many previously reported platinum-modified COFs, metal-containing inorganic photocatalysts, and their composites.

[0106] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0107] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0108] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this application, and these should all be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer, characterized in that, It has the structural unit shown in Equation I: ； Among them, X1 is simultaneously C or N; X2 is simultaneously C or N; X3 is simultaneously C or N.

2. The method for preparing the two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer as described in claim 1, characterized in that, The two-dimensional covalent organic framework material based on the tricyclic quinazoline monomer was prepared by reacting the monomers with the monomers with the structure shown in Formula II and Formula III under solvothermal conditions using a Schiff base reaction. ； In the structural monomer shown in Equation III, X can be either C or N.

3. The method for preparing a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer according to claim 2, characterized in that, The molar ratio of the monomers in the structure shown in Formula II to those in the structure shown in Formula III is 1:(0.9-1.2).

4. The method for preparing a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer according to claim 2, characterized in that, The solvent for the solvothermal reaction is mesitylene and / or 1,4-dioxane; The molar volume ratio of the monomer and solvent in the structure shown in Formula II is (10-80) μmol: 1 mL.

5. The method for preparing a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer according to claim 2, characterized in that, The reaction is carried out in the presence of acetic acid, with the concentration of acetic acid being 5-7 mol / L and the amount of acetic acid added being 5%-15% of the solvent volume.

6. The method for preparing a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer according to claim 2, characterized in that, The reaction conditions are: react at 100-140℃ for 12-120h.

7. The method for preparing a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer according to claim 2, characterized in that, The monomer with the structure shown in Formula II is prepared by the following method: 。 8. The method for preparing a two-dimensional covalent organic framework material based on a tricyclic quinazoline monomer according to claim 7, characterized in that, The reaction conditions were as follows: tris(dibenzylideneacetone)dipalladium was used as a catalyst, 1,1'-binaphthyl-2,2'-bis(diphenylphosphine) was used as the catalyst organic ligand, toluene was used as the solvent, sodium tert-butoxide was used as the base, and the reaction was carried out at 100-130℃.

9. The application of the two-dimensional covalent organic framework material based on tricyclic quinazoline monomers as described in any one of claims 1-8 as a photocatalytic catalyst for hydrogen production from water.

10. The application according to claim 9, characterized in that, The photocatalytic hydrogen production system is as follows: the two-dimensional covalent organic framework material based on the tricyclic quinazoline monomer as described in any one of claims 1-8 is used as the catalyst, ruthenium tripyridine is used as the photosensitizer, triethylamine is used as the electron sacrificial agent, acetonitrile and water are used as the solvent, and LED white light is used as the light source.

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