An aldehyde monomer, its preparation method and application in the preparation of two-dimensional covalent organic framework materials

Abstract

The present invention provides an aldehyde monomer, a preparation method thereof, and an application thereof in the preparation of two-dimensional covalent organic framework materials. This aldehyde monomer has a strong electron-donating ability and can polymerize with an amino monomer having an electron-accepting ability, thereby obtaining a novel two-dimensional covalent organic framework material. This two-dimensional covalent organic framework material has the characteristics of low density and large specific surface area, has a strong ability to give and induce charge transfer, can show donor-acceptor interactions of different intensities in a two-dimensional plane, can effectively form the separation and transfer of electron-hole pairs, and is conducive to the dissociation and separation of semiconductor photoexcited exciton pairs. Therefore, it is expected to be applied in the fields of light-emitting devices, photocatalysis, and optoelectronic transmission, etc.

Description

Technical Field

[0001] The present invention belongs to the fields of organic synthesis and preparation of functional materials, and specifically includes an aldehyde monomer, a preparation method thereof, and an application thereof in the preparation of two-dimensional covalent organic framework materials. Background Art

[0002] Covalent Organic Framework (COF) materials are a class of porous materials formed by connecting organic molecules through covalent bonds, and are porous organic polymers that have been continuously developed and received much attention in recent years. COF materials have the advantages of predictable and adjustable structures. Compared with traditional porous materials, their compositions are more flexible and easier to functionalize, so they show good application prospects in energy, catalysis and other aspects. For example, by connecting electron-rich and electron-donating units (donor units) with electron-deficient and electron-accepting units (acceptor units) in the conjugated framework of two-dimensional COF materials, efficient intra-layer charge transfer between donors and acceptors can effectively promote charge separation and transfer. For polymer semiconductor materials with photo-generated electron activity, it can improve their photocatalytic efficiency, making COF designed based on donor-acceptor interactions a very promising photocatalytic material.

[0003] The azatriphenylene units developed from the commonly used traditional electron-donating unit triphenylamine all have very strong electron-donating abilities and have been preliminarily applied in the field of photoluminescence. Recently, they have also begun to be incorporated into the design and synthesis of porous polymers, but there are currently no relevant reports on using their strong donor characteristics to construct donor-acceptor type COF materials. Summary of the Invention

[0004] Aiming at the above problems existing in the prior art, the first object of the present invention is to provide an aldehyde monomer for preparing covalent organic framework materials. This aldehyde monomer has a strong electron-donating ability and can polymerize with an amino monomer having an electron-accepting ability to form a conjugated structure.

[0005] The second object of the present invention is to provide a preparation method for the above-mentioned aldehyde monomer.

[0006] The third object of the present invention is to provide a two-dimensional covalent organic framework material. This two-dimensional covalent organic framework material has a very strong ability to give and induce charge transfer, can show different intensities of donor-acceptor interactions in the two-dimensional plane, can effectively form the separation and transfer of electrons and holes, and is conducive to the dissociation and separation of semiconductor photo-generated excitons.

[0007] The fourth object of the present invention is to provide a preparation method for the above-mentioned two-dimensional covalent organic framework material.

[0008] The fifth object of the present invention is to provide an application of the two-dimensional covalent organic framework material as described above in the preparation of light-emitting devices, optoelectronic transmission materials and photocatalysts.

[0009] To achieve the above first object, the technical solutions adopted by the present invention include:

[0010] The present invention discloses an aldehyde monomer for preparing a covalent organic framework material, and the structural general formula of the aldehyde monomer is shown in the following formula I:

[0011]

[0012] Wherein, X is selected from any one of O, S, and C(CH3)2.

[0013] To achieve the above second object, the technical solutions adopted by the present invention include:

[0014] The present invention discloses a preparation method for preparing the above-mentioned aldehyde monomer, which includes the following steps:

[0015] Add compound a, compound b, potassium carbonate and a palladium catalyst into a reactor, add 1,4-dioxane and deoxygenated deionized water under nitrogen protection, react at 90-120 °C for 24-36 h, after the reaction is completed, wash with saturated brine, extract with dichloromethane, rotary evaporate the organic phase, and purify by basic alumina chromatography to obtain compound c;

[0016] Disperse compound c with acetonitrile, add water and concentrated hydrochloric acid, reflux and react for 18-24 h, after the reaction is completed, add it to water, and filter and wash to obtain;

[0017] Wherein, compound a is Compound b is Compound c is

[0018] X is selected from any one of O, S, and C(CH3)2.

[0019] Furthermore, the molar ratio of compound a to compound b is 1:3.5-4.5; for example, the molar ratio of compound a to compound b can be 1:3.5, 1:4, 1:4.5, etc.

[0020] Furthermore, compound b, namely 4,4,5,5-tetramethyl-2-[4-(4,4,5,5-tetramethyl-1,3-dioxolan-2-yl)phenyl]-1,3,2-dioxaborolane, is purchased from Shanghai Bide Pharmaceutical Technology Co., Ltd.;

[0021] The palladium catalyst can be selected from bis(triphenylphosphine)palladium dichloride, which is purchased from Shanghai Bide Pharmaceutical Technology Co., Ltd.

[0022] Furthermore, the molar ratio of the compound a to the catalyst is 1:0.05 - 0.20; exemplarily, the molar ratio of the compound a to the catalyst can be 1:0.05, 1:0.1, 1:0.15, 1:0.2, etc.

[0023] Furthermore, the molar ratio of the compound a to potassium carbonate is 1:7 - 10; exemplarily, the molar ratio of the compound a to potassium carbonate can be 1:7, 1:8, 1:9, 1:10, etc.

[0024] To achieve the above third object, the technical solution adopted by the present invention includes:

[0025] The present invention discloses a two-dimensional covalent organic framework material prepared from the aldehyde monomer as described above. The general formula of the basic structural unit of the two-dimensional covalent organic framework material is shown as follows:

[0026]

[0027] Among them, X is selected from any one of O, S, and C(CH3)2;

[0028] A1, A2, and A3 can be the same or different, and each independently represents any one of CH and N;

[0029] represents a connecting bond.

[0030] This two-dimensional covalent organic framework material is formed by polymerizing and interconnecting an aldehyde monomer with a structure shown in Formula I and an amino monomer with a structure shown in Formula II in a two-dimensional plane to form a long-range ordered two-dimensional hexagonal structure. The specific connection method is: each aldehyde building unit of the Formula I structure is connected to three adjacent amino building units of the Formula II structure, and each amino building unit of the Formula II structure is connected to an adjacent aldehyde building unit of the Formula I structure, and thus continuously extends and polymerizes infinitely in the two-dimensional plane to form a two-dimensional conjugated network and regular and ordered pores. The present invention only provides a basic structural unit of the two-dimensional covalent organic framework material for display;

[0031] Among them, the general structural formula of the amino monomer is shown as Formula II below:

[0032]

[0033] A1, A2, and A3 can be the same or different, and each independently represents any one of CH and N.

[0034] The two-dimensional covalent organic framework material is developed from the commonly used traditional electron donor unit triphenylamine. It is a novel covalent organic framework material structure based on the azaheptacene unit, with the characteristics of low density and large specific surface area. Aldehyde monomers (Formula I) with strong electron-giving ability and amino monomers (Formula II) with different electron-accepting abilities are the core components to form a conjugated structure, and different degrees of charge transfer and charge separation can be formed in the two-dimensional plane. Under the excitation of light, excitons are generated in the organic semiconductor, and the strong charge transfer state can help the excitons fully dissociate to form more carriers such as free electrons and holes, so that this new two-dimensional covalent organic framework material has great potential for applications in fields such as light-emitting devices, photocatalysis, and optoelectronic transmission.

[0035] Furthermore, the structural unit of the two-dimensional covalent organic framework material is selected from any one of the following structures:

[0036]

[0037]

[0038]

[0039] To achieve the above fourth object, the technical solution adopted by the present invention includes:

[0040] The present invention discloses a preparation method of the two-dimensional covalent organic framework material as described above, including the following steps:

[0041] Mix the amino monomer, the aldehyde monomer as described above, a catalyst and a solvent evenly, then seal and react in a vacuum environment. After the reaction is completed, filter to obtain a crude product, and the crude product is obtained after washing and Soxhlet extraction.

[0042] Among them, the general structural formula of the amino monomer is shown as Formula II below:

[0043]

[0044] A1, A2, and A3 may be the same or different, and each independently represents any one of CH and N.

[0045] Furthermore, the structure of the amino monomer can be selected from one of the following structures:

[0046]

[0047] Further, the molar ratio of the aldehyde monomer to the amino monomer is 0.8 - 1.2:1.1 - 1.5; exemplarily, the molar ratio of the aldehyde monomer to the amino monomer can be 0.8:1.1 - 1.5, 0.9:1.1 - 1.5, 1:1.1 - 1.5, 1.1:1.1 - 1.5, 1.2:1.1 - 1.5, etc.

[0048] Further, the reaction temperature is 110 - 135 °C and the reaction time is 48 - 96 h.

[0049] Further, the catalyst is selected from aqueous acetic acid solution with a concentration of 3 - 6 mol / L.

[0050] Further, the volume of the catalyst is 5 - 20% of the volume of the solvent used in the reaction system.

[0051] Further, the solvent is a mixed solvent of 1,2 - dichlorobenzene and n - butanol.

[0052] Further, the volume ratio of 1,2 - dichlorobenzene to n - butanol is 1 - 5:1 - 4; exemplarily, the volume ratio of 1,2 - dichlorobenzene to n - butanol can be 1:1 - 4, 2:1 - 4, 3:1 - 4, 4:1 - 4, 5:1 - 4, etc.

[0053] Further, the molar volume ratio of the aldehyde monomer to the solvent is 50 μmol:3 - 6 mL.

[0054] Further, the washing liquid used for washing includes but is not limited to one or more of methanol, N,N - dimethylformamide, acetonitrile, tetrahydrofuran, dichloromethane, and n - hexane.

[0055] Further, Soxhlet extraction means continuously eluting the crude product of the two - dimensional covalent organic framework material with a Soxhlet extraction solvent. In a specific embodiment, the selected Soxhlet extraction solvent is anhydrous tetrahydrofuran.

[0056] To achieve the above - mentioned fifth object, the technical solution adopted by the present invention includes:

[0057] The present invention discloses an application of the two - dimensional covalent organic framework material as described above in the preparation of light - emitting devices, optoelectronic transmission materials, and photocatalysts.

[0058] Advantages of the present invention:

[0059] The present invention discloses an aldehyde monomer, its preparation method, and its application in the preparation of two-dimensional covalent organic framework materials. In the present invention, a new type of two-dimensional covalent organic framework material is developed. This two-dimensional covalent organic framework material is developed from the commonly used traditional electron donor unit triphenylamine and has a new covalent organic framework material structure based on the azatriphenylene unit. Specifically, it refers to a conjugated structure formed by polymerization with an aldehyde monomer (Formula I) having a strong electron-donating ability and an amino monomer (Formula II) having different electron-accepting abilities as the core components. This two-dimensional covalent organic framework material can form different degrees of charge transfer and charge separation in the two-dimensional plane. Under the excitation of light, excitons are generated in the organic semiconductor, and the strong charge transfer state can help the excitons fully dissociate to form more free electrons and holes and other carriers, so that this new two-dimensional covalent organic framework material has great potential for applications in fields such as light-emitting devices, photocatalysis, and optoelectronic transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The following further elaborates on the specific embodiments of the present invention with reference to the accompanying drawings.

[0061] Figure 1 1H NMR spectrum of TON-3PhCHO prepared in Example 1;

[0062] Figure 2 Schematic diagram of the structural modeling simulation of TON-triPh-Triazine COF prepared in Example 2;

[0063] Figure 3 PXRD diffraction image, Pawley refinement, and comparison with the same model of TON-triPh-Triazine COF prepared in Example 2;

[0064] Figure 4 N2 adsorption-desorption curve of TON-triPh-Triazine COF prepared in Example 2;

[0065] Figure 5 BET method calculated surface area diagram of TON-triPh-Triazine COF prepared in Example 2;

[0066] Figure 6 Pore size distribution diagram of TON-triPh-Triazine COF prepared in Example 2;

[0067] Figure 7 Solid state 13C NMR spectrum of TON-triPh-Triazine COF prepared in Example 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0068] To illustrate the present invention more clearly, the present invention will be further described below in conjunction with specific embodiments and the accompanying drawings. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0069] Example 1

[0070] Synthesis of aldehyde monomer TON-3PhCHO

[0071]

[0072] TON-3Br (524.0 mg, 1 mmol), 4,4,5,5-tetramethyl-2-[4-(4,4,5,5-tetramethyl-1,3-dioxolan-2-yl)phenyl]-1,3,2-dioxaborolane (1.33 g, 4 mmol), potassium carbonate (1.1 g, 8 mmol) and PdCl2(PPh3)2 (70.2 mg, 0.1 mmol) were placed in a two-necked flask. Subsequently, 100 ml of 1,4-dioxane was injected into the two-necked flask under nitrogen protection, and 10 ml of deoxygenated distilled water was added. Then the mixture was heated at 100 °C for 24 h. After the reaction was completed, it was cooled, the reaction product was washed with saturated brine and extracted with dichloromethane. The obtained organic phase was distilled under reduced pressure to remove the solvent, and purified by basic alumina chromatography using dichloromethane as the eluent to obtain 530 mg of a pale yellow solid product 1, with a yield of 59%.

[0073] The 530 mg of solid product 1 was redispersed in 60 mL of acetonitrile, 10 mL of water and 10 mL of concentrated hydrochloric acid were added, and the mixture was heated under reflux for 24 h. After the reaction was completed, it was cooled, poured into a large amount of water, and the red solid was filtered. It was washed several times with methanol and tetrahydrofuran to obtain bright red solid TON-3PhCHO (352 mg, yield 86%).

[0074] The prepared TON-3PhCHO was subjected to liquid nuclear magnetic resonance spectroscopy test using a German Bruker Ascend 600 nuclear magnetic resonance spectrometer (the solvent was d 6 -DMSO), see Figure 1 , the singlet at 7.11 ppm was for the 6 hydrogen atoms on the 4,8,12-trioxa-3a2-azadibenzo[cd,mn]pyrene ring, the multiplet at 7.91 - 7.95 ppm was for the total 12 hydrogen atoms on the substituted benzene ring, and the singlet at 10.04 ppm was for the 3 hydrogen atoms of the aldehyde group. The area ratio of each peak corresponded one by one to the number ratio of various hydrogen atoms in the TON-3PhCHO structure. Therefore, it was confirmed that the aldehyde monomer TON-3PhCHO was successfully synthesized.

[0075] The MALDI-MS mass spectrometry test of the prepared TON-3PhCHO was carried out using a Bruker Autoflex III time-of-flight mass spectrometer made in Germany. The mass-to-charge ratio of the molecular ion peak of the measured compound was 599.03, which was basically consistent with the relative molecular mass of 599.14 of TON-3PhCHO in theory, verifying the success of the synthesis again.

[0076] Example 2

[0077] Preparation of two-dimensional covalent organic framework material TON-triPh-Triazine COF

[0078] TON-3PhCHO (60.0 mg, 0.1 mmol) prepared in Example 1 and Triazine-3biPhNH2 (58.3 mg, 0.1 mmol) were added to a Schlenk tube, and then 3 mL of n-butanol, 3 mL of 1,2-dichlorobenzene and 0.6 mL of acetic acid aqueous solution (6 M) were added. Under liquid nitrogen cooling, the freeze-pump-thaw operation was repeated three times to fully degas the mixture to a vacuum state. After perfect sealing, it was placed in an oil bath at 120 °C and reacted for 72 h. After the reaction, it was naturally cooled, and the precipitate in the Schlenk tube was filtered out and washed with methanol, N,N-dimethylformamide, acetonitrile, tetrahydrofuran, dichloromethane and n-hexane. Then the obtained solid was eluted with anhydrous tetrahydrofuran as the Soxhlet extraction solvent in a Soxhlet extractor for 24 h, and finally dried in vacuo at 60 °C for 24 h to obtain the imine-type two-dimensional covalent organic framework material TON-triPh-Triazine COF.

[0079] Figure 2 It is the structural modeling result of TON-triPh-Triazine COF by using the software Material Studio. It can be seen from the figure that TON-triPh-Triazine COF has a pore structure of 3.85 nm.

[0080] The powder X-ray diffraction test of the prepared TON-triPh-Triazine COF was carried out using a Bruker D8 Advance diffractometer made in Germany, and the ray was the Kα ray generated by a copper target. The scanning range was 2°-40°, and by using Figure 2 the established structural model of TON-triPh-Triazine COF, Pawley refinement was performed on the XRD data obtained from the experiment. Through Figure 3It can be seen that the main diffraction peaks of TON-triPh-Triazine COF are 2.78° and 4.78°, corresponding to the (100) and (110) crystal planes respectively. In addition, there is a weak diffraction signal corresponding to the (001) crystal plane distributed at 24°, reflecting the stacking perpendicular to the two-dimensional plane. The experimental XRD results and the XRD results of the simulated AA stacking model show good matching, proving the successful preparation of the new imine-based two-dimensional covalent organic framework material TON-triPh-Triazine COF.

[0081] The nitrogen adsorption-desorption isotherm test of the prepared TON-triPh-Triazine COF was carried out using a Quantachrome Quadrasorb SI-MP specific surface area and porosity analyzer in the United States. The samples used for the test were degassed in vacuum at 60°C for a long time for measurement. The nitrogen adsorption-desorption isotherm was measured at 77.35 K, and was used to calculate the specific surface area of the sample (calculated according to the Brunauer-Emmett-Teller theory) and the pore size distribution (calculated according to the Barret-Joyner-Halenda model). Through Figure 4 、 5 、6, it can be seen that TON-triPh-Triazine COF is a mesoporous material. The calculated specific surface area is 507.3 m 2 / g, and the pore size is 3.83 nm. The pore size calculated by the BJH model is very close to the pore size (3.85 nm) in the AA stacking model, verifying again the success of the synthesis of TON-triPh-Triazine COF and the characteristics of AA stacking.

[0082] The solid-state nuclear magnetic resonance spectroscopy test of the prepared TON-triPh-Triazine COF was carried out using a Bruker AVANCE III HD 500 solid-state nuclear magnetic resonance spectrometer in Germany. Through Figure 7 it can be seen that the characteristic signal of the carbon atom in -C=N- appears at 160 ppm, confirming the existence of -C=N- in the solid structure, indicating the existence of polymerized imine bonds, and also indicating the successful synthesis of TON-triPh-Triazine COF.

[0083] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. An aldehyde monomer for preparing covalent organic framework materials, characterized in that, The structural general formula of the aldehyde group monomer is as shown in Formula I below: I； Among them, X is selected from any one of O and S.

2. The preparation method of the aldehyde group monomer according to claim 1, characterized in that, It includes the following steps: Add compound a, compound b, potassium carbonate and a palladium catalyst into a reactor. Under nitrogen protection, add 1,4-dioxane and deoxygenated deionized water, and react at 90 - 120 °C for 24 - 36 h. After the reaction is completed, wash with saturated brine, extract with dichloromethane, rotary evaporate the organic phase, and purify by basic alumina chromatography to obtain compound c; Disperse compound c with acetonitrile, add water and concentrated hydrochloric acid, reflux and react for 18 - 24 h. After the reaction is completed, add it to water, filter and wash to obtain the aldehyde group monomer described in Claim 1; Among them, compound a is ; compound b is ; Compound c is .

3. The preparation method according to claim 2, characterized in that, The molar ratio of compound a to compound b is 1:3.5 - 4.

5.

4. A two-dimensional covalent organic framework material, characterized in that The general formula of the basic structural unit of the two-dimensional covalent organic framework material is as shown below: ； Among them, X is selected from any one of O, S, and C(CH3)2; A1, A2, and A3 may be the same or different, and each independently represents any one of CH and N; Represents a connection key.

5. The two-dimensional covalent organic framework material according to claim 4, wherein The structural unit of the two-dimensional covalent organic framework material is selected from any one of the following structures: 。 6. The preparation method of the two-dimensional covalent organic framework material according to claim 4 or 5, characterized in that, It includes the following steps: Mix the amino monomer, the aldehyde group monomer as described in Claim 1, a catalyst and a solvent evenly, then seal and react in a vacuum environment. After the reaction is completed, filter to obtain a crude product. The crude product is washed and Soxhlet extracted to obtain it; Among them, the structural general formula of the amino monomer is as shown in Formula II below: II; A1, A2, and A3 may be the same or different, and each independently represents any one of CH and N.

7. The preparation method according to claim 6, characterized in that, The molar ratio of the aldehyde group monomer to the amino monomer is 0.8 - 1.2:1.1 - 1.

5.

8. The preparation method according to claim 6, characterized in that, The reaction temperature is 110 - 135 °C, and the reaction time is 48 - 96 h.

9. The preparation method according to claim 6, wherein, The catalyst is selected from an aqueous acetic acid solution; The solvent is a mixed solvent of 1,2-dichlorobenzene and n-butanol.

10. Use of the two-dimensional covalent organic framework material as described in Claim 4 or 5 in the preparation of light-emitting devices, optoelectronic transmission materials, and photocatalysts.

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