Porous aromatic skeleton based on tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural element as well as preparation method and application of porous aromatic skeleton

Abstract

The invention relates to a porous aromatic skeleton based on a tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural element as well as a preparation method and application of the porous aromatic skeleton. The porous aromatic skeleton takes tetraphenylmethane-aromatic imide-tetraphenylmethane with a hexabromo-substituted dumbbell-shaped structure as the structural element; the compound is obtained by performing Yamamoto coupling with a tetrabromo-substituted tetraphenylmethane structural element according to different molar ratios x, wherein the value range of x is 0-1. Compared with the prior art, the aromatic imide unit introduced into the structure endows the material with the characteristics of an organic porous material and a photoelectric functional material. Therefore, the material can be applied to the fields of adsorption separation of gas and micropollutants, photodegradation of pollutants, photocatalytic reaction and the like.

Description

Technical Field

[0001] The present invention relates to the technical fields of porous materials and optoelectronic functional materials, and in particular to a porous aromatic framework based on a tetra-phenylmethane-aromatic imide-tetra-phenylmethane dumbbell-shaped structural unit, and a preparation method and application thereof. Background Art

[0002] Tetra-phenylmethane has a unique diamond-like three-dimensional structure. The three-dimensional topological structure of its tetrahedron can fully expand the molecular skeleton, which is conducive to obtaining a higher specific surface area. The porous aromatic frameworks (PAFs) constructed with tetra-phenylmethane as the structural unit have a three-dimensional pore structure, good structural stability, easy post-modification, and high specific surface area. The highest specific surface area of the porous aromatic framework PAF-1 reported by the research group of Guangshan Zhu reached 5600 m 2 g -1 (Angew.Chem.Int.Ed.2009,48,9457-9460). Porous aromatic frameworks have been widely used in the fields of gas and pollutant adsorption, separation, drug loading, and catalysis.

[0003] Currently reported porous aromatic frameworks based on tetra-phenylmethane have relatively simple structures. The modification of the framework structure is mainly to introduce simple functional groups such as amino and carboxyl groups on the benzene ring, mainly to adjust the pore size and polarity of the porous framework, resulting in their application fields mainly concentrated in the fields of gas and pollutant adsorption. In addition, due to their three-dimensional topological structure, porous organic polymers based on tetra-phenylmethane are prone to form structural interpenetration and structural defects during cross-coupling such as Sonogashira and Suzuki, resulting in a decrease in specific surface area, thereby limiting their application in the adsorption field.

[0004] Patent CN106279640A discloses a preparation method of a nitro-functionalized porous aromatic framework material. Using a nitrated haloaromatic compound (synthesized by introducing halogen atoms into tetra-phenylmethane) as a raw material, the nitro-functionalized PAF materials are prepared by reacting with copper under heating conditions. The method is simple and low-cost, but its BET specific surface area is only 610 m 2 / g, still limiting its application in the adsorption field. Summary of the Invention

[0005] The purpose of the present invention is to provide a porous aromatic framework based on a tetra-phenylmethane-aromatic imide-tetra-phenylmethane dumbbell-shaped structural unit, and a preparation method and application thereof. The porous aromatic framework simultaneously has optoelectronic functional characteristics, porous characteristics, and fluorescence characteristics, and can be applied to the fields of adsorption and separation of micro-pollutants, photodegradation of pollutants, and photocatalytic reactions.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] On the one hand, the present invention provides a porous aromatic framework based on a tetra-phenylmethane-aromatic imide-tetra-phenylmethane dumbbell-shaped structural unit, which is obtained by Yamamoto coupling of a hexabromo-substituted tetra-phenylmethane-aromatic imide-tetra-phenylmethane dumbbell-shaped structural unit and a tetrabromo-substituted tetra-phenylmethane structural unit in different molar ratios, and its structural general formula is:

[0008]

[0009] Wherein, is an aromatic imide or aromatic lactam;

[0010] The x is the molar ratio of the tetra-phenylmethane-aromatic imide-tetra-phenylmethane dumbbell-shaped structural unit to the tetra-phenylmethane structural unit, and its value range is: 0 - 1.

[0011] Preferably, the porous aromatic framework simultaneously has optoelectronic functional properties, porous material properties and fluorescence properties.

[0012] More preferably, the specific surface area of the porous aromatic framework is 2471 mg g -1 -291 mg g -1 .

[0013] Preferably, the aromatic imide includes PMDI (phthalimide), NDI (naphthalimide), PBI (perylene diimide), DPP (pyrrolopyrrole dione), and the porous aromatic framework includes PAF-xPMDI, PAF-xNDI, PAF-xPBI, PAF-xDPP, and their structural formulas are respectively:

[0014]

[0015]

[0016] Wherein, R is a hydrogen atom or a chlorine atom;

[0017]

[0018] Preferably, when x is between 0 and 1, the porous aromatic framework is obtained by carrying out a Yamamoto coupling copolymerization reaction on a hexabromo-substituted tetra-phenylmethane-aromatic imide-tetra-phenylmethane dumbbell-shaped structural unit and a tetrabromo-substituted tetra-phenylmethane structural unit, and the porous aromatic framework is a copolymer.

[0019] Preferably, when x = 0, the porous aromatic framework is prepared by Yamamoto coupling homopolymerization of a tetra-bromo-substituted tetraphenylmethane structural motif, and the resulting porous aromatic framework is a homopolymer.

[0020] Preferably, when x = 1, the porous aromatic framework is prepared by Yamamoto coupling homopolymerization of a hexa-bromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural motif, and the resulting porous aromatic framework is a homopolymer.

[0021] More preferably, when x = 1, the porous aromatic framework includes PAF-PMDI, PAF-NDI, PAF-PBI, PAF-DPP, and their structural formulas are as follows:

[0022]

[0023]

[0024] Among them, R = H or Cl;

[0025]

[0026] Preferably, the hexa-bromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural motif includes TPM-PMDI-6Br, TPM-NDI-6Br, TPM-PBI-6Br or TPM-DPP-6Br, and their structural formulas are as follows:

[0027]

[0028] Preferably, the tetra-bromo-substituted tetraphenylmethane structural motif is TPM-4Br, and its structural formula is as follows:

[0029]

[0030] Preferably, the hexa-bromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural motif is formed by reacting TPM-NH2-3Br with the corresponding aromatic anhydride or aromatic lactone and connecting through an imide bond or an amide bond.

[0031] Preferably, the synthesis route of TPM-PMDI-6Br is as follows:

[0032]

[0033] Preferably, the synthesis route of TPM-NDI-6Br is as follows:

[0034]

[0035] Preferably, the synthetic route of the TPM-PBI-6Br is as follows:

[0036]

[0037] Preferably, the synthetic route of the TPM-DPP-6Br is as follows:

[0038]

[0039] In a second aspect, the present invention also provides a method for preparing the porous aromatic framework based on the tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit, comprising the following steps:

[0040] S1: Under anhydrous and anaerobic conditions, dissolve the hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit and the tetrabromo-substituted tetraphenylmethane structural unit in an organic solvent according to a molar ratio of x, use bis-(1,5-cyclooctadiene) nickel as a catalyst, and 2,2-bipyridine and 1,5-cyclooctadiene as ligands to carry out the Yamamoto coupling reaction;

[0041] S2: Quench the reaction with concentrated hydrochloric acid, wash and vacuum dry the obtained product to obtain the porous aromatic framework.

[0042] Preferably, in step S1, the organic solvent is a mixed solvent of N,N-dimethylformamide (anhydrous DMF) and tetrahydrofuran (anhydrous THF), the volume ratio of N,N-dimethylformamide to tetrahydrofuran is 1:2 - 5:1, and the reaction time is 40 - 56 h.

[0043] More preferably, in step S1, the reaction time is 48 h.

[0044] Preferably, in step S1, the anhydrous and anaerobic conditions mean that the reaction is carried out under a nitrogen protection atmosphere.

[0045] Preferably, in step S1, the 2,2-bipyridine and 1,5-cyclooctadiene are a solution of 2,2-bipyridine and 1,5-cyclooctadiene in anhydrous DMF.

[0046] Preferably, in step S2, the concentration of the concentrated hydrochloric acid is 9 - 13 M.

[0047] More preferably, in step S2, the concentration of the concentrated hydrochloric acid is 11 M.

[0048] Preferably, in step S2, the washing means washing successively with dichloromethane, tetrahydrofuran, water and methanol.

[0049] Preferably, in step S2, the temperature of the vacuum drying is 80 - 120 °C and the time is 20 - 28 h

[0050] Further preferably, in step S2, the temperature of the vacuum drying is 100 °C and the time is 24 h.

[0051] Further preferably, the preparation method of the porous aromatic framework based on the tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit includes the following steps:

[0052] Dissolve 2,2'-bipyridine and 1,5-cyclooctadiene in anhydrous DMF, stir at room temperature for 0.5 h, and then dissolve the hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit (TPM-PMDI-6Br, TPM-NDI-6Br, TPM-PBI-6Br or TPM-DPP-6Br) and the tetrabromo-substituted tetraphenylmethane structural unit (TPM-4Br) in different molar ratios x in anhydrous DMF and anhydrous THF. Using bis-(1,5-cyclooctadiene)nickel as a catalyst, carry out the Yamamoto coupling reaction under nitrogen protection. After reacting at room temperature for 48 h, quench the reaction with dilute hydrochloric acid. Wash the crude product repeatedly with dichloromethane, tetrahydrofuran, water and methanol, and dry it under vacuum. The obtained solid is the target porous aromatic framework (PAF-xPMDI, PAF-xNDI, PAF-xPBI or PAF-xDPP).

[0053] In a third aspect, the present invention also provides an application of the porous aromatic framework based on the tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit, including applications in the fields of adsorption and separation of gases and micro-pollutants, photocatalytic degradation of pollutants and photocatalytic reaction technology.

[0054] Literature reports that the porous aromatic framework obtained by Yamamoto coupling homopolymerization of tetraphenylmethane has a relatively high specific surface area compared with other polymerization methods (Chem. Rev. 2020, 120, 8934 - 8986).

[0055] Aromatic imides contain a relatively large coplanar structure and electron-withdrawing groups of imides, and are widely used in the construction of organic optoelectronic functional materials, such as organic solar cells, organic field-effect transistors, and fluorescent probes (Chem. Rev. 2014, 114, 8943 - 9021; Adv. Mater. 2014, 26, 6965 - 6977). Common aromatic imide or aromatic amide structures include: pyromellitic diimide (PMDI), naphthalene diimide (NDI), perylene bisimide (PBI), and diketopyrrolopyrrole (DPP). Naphthalene diimide is a polycyclic aromatic hydrocarbon fluorescent group with strong electron affinity, excellent photostability, and tunable fluorescence properties, and is commonly used in organic electronic devices, chemical sensing, and molecular recognition. Perylene bisimide is a polycyclic aromatic hydrocarbon fluorescent dye with high fluorescence quantum yield, excellent light and chemical stability, and is widely used in organic optoelectronic materials, bioimaging, and chemical sensors. Diketopyrrolopyrrole is widely used in organic photovoltaic materials and solar cells due to its strong electron-withdrawing ability, excellent coplanarity, and photophysical properties. In the present invention, a dumbbell-shaped tetraphenylmethane-aromatic imide-tetraphenylmethane structural motif is designed by introducing tetraphenylmethane at the imide positions at both ends of common aromatic imides, and Yamamoto coupling homopolymerization or copolymerization with tetraphenylmethane is used to adjust the proportion of aromatic imides in the porous skeleton. After introducing different proportions of aromatic imides into the porous skeleton, the porous material can have unique optoelectronic properties and expand its application range.

[0056] Starting from the design of the material structure, the present invention introduces aromatic imides with optoelectronic functional characteristics into the porous aromatic skeleton, enriching the structural properties of the aromatic porous skeleton, endowing it with both the optoelectronic functional characteristics of aromatic imides and the porous characteristics such as the high specific surface area of the porous aromatic skeleton, and expanding its application range. In the tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural motif, the tetraphenylmethane at both ends wraps the aromatic imide with a large conjugated plane in the middle, which can effectively inhibit the fluorescence quenching caused by the π-π aggregation of aromatic imides, making the porous aromatic skeleton also have fluorescence characteristics. Introducing aromatic imides can also increase the polarity of the skeleton and improve the interaction force of the porous aromatic skeleton on polar molecules. Adjusting the proportion of the tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped monomer in the copolymer can optimize the specific surface area, fluorescence quantum efficiency, and structural polarity of the porous aromatic skeleton.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] (1) The present invention provides a porous aromatic framework, which is constructed by Yamamoto coupling reaction (homopolymerization or copolymerization) based on a hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit and a tetrabromo-substituted tetraphenylmethane structural unit, and has optoelectronic functional characteristics, porous characteristics and fluorescence characteristics at the same time.

[0059] (2) By introducing tetraphenylmethane at the imide positions at both ends of a common aromatic imide to construct a dumbbell-shaped tetraphenylmethane-aromatic imide-tetraphenylmethane structural unit and introducing the common aromatic imide into the porous aromatic framework, the present invention has both the optoelectronic functional characteristics and fluorescence properties of aromatic imide and porous characteristics such as the high specific surface area of the porous aromatic framework.

[0060] (3) By adjusting the proportion of the tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped monomer in the copolymer, the specific surface area, fluorescence quantum efficiency and structural polarity of the porous aromatic framework can be further optimized. The specific surface area of the porous aromatic framework of the present invention can reach 2471 mg g -1 -291 mg g -1 , and the synthesized PAF-xDPP exhibits fluorescence characteristics under 365 nm ultraviolet light.

[0061] (4) Since the present invention has both optoelectronic functional characteristics and porous characteristics, it can be applied to fields such as the adsorption and separation of micro-pollutants, the photocatalytic degradation of pollutants and photocatalytic reactions. For example, the synthesized PAF-5%DPP is used for the adsorption of crystal violet, and PAF-PBI is used for the photocatalytic degradation of methylene blue and the photocatalytic oxidation of thioether to sulfoxide, and the effects are all good.

[0062] (5) The porous aromatic framework of the present invention is constructed by Yamamoto coupling reaction, forming a rigid and stable porous network structure connected by aromatic rings through carbon-carbon bonds and imide bonds. This structure makes the present invention also have high thermal stability and chemical stability. Description of the Drawings

[0063] Figure 1 Sample photos of the porous aromatic frameworks PAF-xDPP with different feeding ratios in Examples 3-6 under sunlight and 365 nm ultraviolet light;

[0064] Figure 2 Solid-state NMR of PAF-DPP prepared in Example 6 13 13C NMR spectrum;

[0065] Figure 3 Ultraviolet-visible absorption spectra of the solid powders of the porous aromatic frameworks PAF-xDPP with different feeding ratios in Examples 3-6;

[0066] Figure 4 Thermogravimetric analysis diagrams of porous aromatic frameworks PAF-xDPP with different feeding ratios in Examples 3-6;

[0067] Figure 5 Adsorption efficiency diagram of PAF-5%DPP prepared in Example 3 for crystal violet at 25°C;

[0068] Figure 6 Ultraviolet adsorption diagram of PAF-5%DPP prepared in Example 3 for crystal violet in aqueous solution;

[0069] Figure 7 Ultraviolet-visible absorption spectrum diagram of PAF-PBI solid powder prepared in Example 7;

[0070] Figure 8 Physical diagram of photocatalytic degradation of methylene blue by PAF-PBI solid powder prepared in Example 7. Specific implementation mode

[0071] This example is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0072] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0073] A porous aromatic framework based on a tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit, which is obtained by Yamamoto coupling of a hexabromo-substituted dumbbell-shaped tetraphenylmethane-aromatic imide-tetraphenylmethane as a structural unit with a tetrabromo-substituted tetraphenylmethane structural unit in different molar ratios, and its structural general formula is:

[0074]

[0075] Among them, is an aromatic imide or aromatic lactam;

[0076] The x is the molar ratio of the hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit to the tetrabromo-substituted tetraphenylmethane structural unit, and its value range is: 0-1;

[0077] The porous aromatic framework is obtained by carrying out Yamamoto coupling copolymerization on a hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit and a tetrabromo-substituted tetraphenylmethane structural unit; or is prepared by carrying out Yamamoto coupling homopolymerization on a hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit; or is obtained by carrying out Yamamoto coupling homopolymerization on a tetrabromo-substituted tetraphenylmethane structural unit.

[0078] The preparation method is as follows:

[0079] General synthesis steps of the porous aromatic framework:

[0080] Dissolve a hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit (TPM-PMDI-6Br, TPM-NDI-6Br, TPM-PBI-6Br or TPM-DPP-6Br) and a tetrabromo-substituted tetraphenylmethane structural unit (TPM-4Br) in anhydrous DMF and anhydrous THF according to different molar ratios x. Using bis-(1,5-cyclooctadiene) nickel as a catalyst, under the action of 2,2'-bipyridine and 1,5-cyclooctadiene which are also dissolved in anhydrous DMF, react at room temperature under nitrogen protection for 48 hours. After the reaction is completed, quench the reaction solution with dilute hydrochloric acid, filter, and repeatedly wash the filter residue with dichloromethane, tetrahydrofuran, water and methanol. The solid obtained after vacuum drying is the aromatic porous framework (PAF-xPMDI, PAF-xPBI, PAF-xNDI and PAF-xDPP).

[0081] The present invention will be described in detail below with reference to the accompanying drawings and specific examples. The raw materials or reactants used in the examples are all commercially available.

[0082] Example 1

[0083] Synthesis of TPM-NH2-3Br

[0084]

[0085] Dissolve 4-tritylaniline (2.02 g, 6 mmol) and potassium iodide (498 mg, 0.3 mmol) in 20 mL of tetrahydrofuran, slowly add dropwise 70% aqueous tert-butyl hydroperoxide solution (2.19 mL, 22.8 mmol), heat and react at 80 °C for 15 h. After the reaction is completed, quench with saturated sodium sulfite solution, wash with brine, extract with ethyl acetate, dry the organic phase with anhydrous sodium sulfate, concentrate by rotary evaporation, and carry out silica gel column chromatography separation with dichloromethane and petroleum ether (1:3, v:v) to obtain 0.61 g of pale yellow 4-tritylnitrobenzene (TPM-NO2) solid (yield: 28%).

[0086]

[0087] 4 - Triphenylmethylnitrobenzene TPM - NO2 (1.0 g, 2.73 mmol) was dissolved in liquid bromine (4 mL, 95.55 mmol), and the reaction was carried out at 55 °C for 2 h. Then it was cooled to 0 °C, and the reaction was quenched with saturated sodium hydroxide solution until the solution became colorless. The reaction solution was extracted with dichloromethane three times, and the organic phase was dried over anhydrous sodium sulfate and then concentrated by rotary evaporation to obtain 1.4 g of crude product TPM - NO2 - 3Br (yield: 96%).

[0088]

[0089] TPM - NO2 - 3Br (1.0 g, 1.66 mmol) and stannous chloride dihydrate (1.86 g, 8.33 mmol) were dissolved in 100 mL of ethanol. 11 M concentrated hydrochloric acid (6.6 mL) was added, and the reaction was heated to 88 °C for 24 h. After cooling to room temperature, saturated sodium hydroxide solution was added dropwise to adjust the pH of the solution to 10. The reaction solution was extracted with dichloromethane three times, and the combined organic phase was dried over anhydrous sodium sulfate and then concentrated by rotary evaporation. The crude product was separated by silica gel column chromatography with dichloromethane and petroleum ether (1:3, v:v) to obtain 0.8 g of pale yellow solid TPM - NH2 - 3Br (yield: 84%).

[0090] Example 2

[0091] Synthesis of hexabromo - substituted tetraphenylmethane - aromatic imide - tetraphenylmethane dumbbell - shaped structural motif

[0092] Synthesis of TPM - PMDI - 6Br:

[0093]

[0094] Compound TPM - NH2 - 3Br (460 mg, 0.8 mmol) and pyromellitic dianhydride (43.6 mg, 0.2 mmol) were added to 4 mL of propionic acid, and the mixture was heated to reflux at 120 °C for 12 h. After the reaction was completed, it was cooled to room temperature, then poured into water, and the precipitated solid was filtered and then washed with a large amount of water. The crude product was separated by silica gel column chromatography with dichloromethane and petroleum ether (1:1, v:v) to obtain 199 mg of the final target product TPM - PMDI - 6Br (yield: 75%).

[0095] Synthesis of TPM - NDI - 6Br:

[0096]

[0097] The compound TPM-NH2-3Br (460 mg, 0.8 mmol) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (54 mg, 0.2 mmol) were added to 4 mL of propionic acid, and the mixture was heated to reflux at 120 °C for 12 h. After the reaction was completed, it was cooled to room temperature, then poured into water, and the precipitated solid was filtered and then washed with a large amount of water. The crude product was separated by silica gel column chromatography with dichloromethane and petroleum ether (1.5:1, v:v) to obtain the final target product TPM-NDI-6Br, 220 mg (yield: 80%).

[0098] Synthesis of TPM-PBI-6Br:

[0099]

[0100] The compound TPM-NH2-3Br (460 mg, 0.8 mmol) and perylene-3,4,9,10-tetracarboxylic dianhydride (106 mg, 0.2 mmol) were added to 4 mL of propionic acid, and the mixture was heated to reflux at 120 °C for 12 h. After the reaction was completed, it was cooled to room temperature, then poured into water, and the precipitated solid was filtered and then washed with a large amount of water. The crude product was separated by silica gel column chromatography with dichloromethane and petroleum ether (1.6:1, v:v) to obtain the final target product TPM-PBI-6Br, 250 mg (yield: 76%).

[0101] Synthesis of TPM-DPP-6Br:

[0102]

[0103] The compound TPM-NH2-3Br (460 mg, 0.8 mmol) and diphenylpyrrolo[3,4-c]pyrrole-1,4-dione (58 mg, 0.2 mmol) were dissolved in 15 mL of dichloromethane, then 1-hydroxybenzotriazole (110 mg, 0.8 mmol), 4-dimethylaminopyridine (98 mg, 0.8 mmol) and N,N'-diisopropylcarbodiimide (101 mg, 0.8 mmol) were added, and the mixture was stirred at 40 °C for 5 days. The reaction solution was extracted three times with dichloromethane and washed repeatedly with saturated brine. The organic phase was concentrated under reduced pressure to obtain a solid, and the solid was washed three times with methanol and filtered to obtain the product TPM-DPP-6Br, 251 mg (yield: 90%)

[0104] Example 3

[0105] Synthesis of PAF-5%DPP (x = 5%):

[0106] 2,2'-Bipyridine (1104 mg, 6 eq), 1,5-cyclooctadiene (939 μL, 6 eq), and bis-(1,5-cyclooctadiene)nickel (1938 mg, 6 eq) were added to a 250 mL round-bottom flask. 25 mL of anhydrous DMF was added thereto, and the mixture was stirred at room temperature for 0.5 h. The monomers TPM-4Br (818.1 mg, 1.2825 mmol) and TPM-DPP-6Br (31.5 mg, 0.0675 mmol) were dissolved in 25 mL of anhydrous DMF and 50 mL of anhydrous THF, and the reaction was carried out at room temperature for 48 h under nitrogen protection. After the reaction was completed, the reaction solution was quenched with 30 mL of 11 M hydrochloric acid, stirred for 2 h, and then filtered. The filter cake was washed repeatedly with 150 mL of dichloromethane, 150 mL of tetrahydrofuran, 150 mL of water, and 150 mL of methanol, and dried in vacuo to obtain 450 mg of a yellow solid (yield 92%).

[0107] Example 4

[0108] Synthesis of PAF-1%DPP (x = 1%):

[0109] 2,2'-Bipyridine (368 mg, 6 eq), 1,5-cyclooctadiene (313 μL, 6 eq), and bis-(1,5-cyclooctadiene)nickel (646 mg, 6 eq) were dissolved in 10 mL of anhydrous DMF, and the mixture was stirred at room temperature for 0.5 h. The monomers TPM-4Br (284.3 mg, 0.4455 mmol) and TPM-DPP-6Br (6.3 mg, 0.0045 mmol) were dissolved in 8 mL of anhydrous DMF and 12 mL of anhydrous THF, and the reaction was carried out at room temperature for 48 h under nitrogen protection. After the reaction was completed, the reaction solution was quenched with 10 mL of 11 M hydrochloric acid, stirred for 2 h, and then filtered. The filter cake was washed repeatedly with 50 mL of dichloromethane, 50 mL of tetrahydrofuran, 50 mL of water, and 50 mL of methanol, and dried in vacuo to obtain 132 mg of a light yellow solid (yield 91%).

[0110] Example 5

[0111] Synthesis of PAF-10%DPP (x = 10%):

[0112] Dissolve 2,2'-bipyridine (348 mg, 6 equiv.), 1,5-cyclooctadiene (296 μL, 6 equiv.), and bis-(1,5-cyclooctadiene)nickel (612.3 mg, 6 equiv.) in 10 mL of anhydrous DMF, stir at room temperature for 0.5 h. Dissolve monomer TPM-4Br (229.7 mg, 0.36 mmol) and monomer TPM-DPP-6Br (55.9 mg, 0.04 mmol) in 8 mL of anhydrous DMF and 12 mL of anhydrous THF, react at room temperature for 48 h under nitrogen protection. After the reaction is completed, quench the reaction solution with 6 mL of 11 M hydrochloric acid, stir for 2 h and then filter. Wash the filter cake repeatedly with 150 mL of dichloromethane, 150 mL of tetrahydrofuran, 150 mL of water, and 150 mL of methanol, and dry in vacuo to obtain 147 mg of a yellow solid (yield 96%)

[0113] Example 6

[0114] Synthesis of PAF-DPP (x = 1):

[0115] Add 2,2'-bipyridine (268 mg, 6.5 equiv.), 1,5-cyclooctadiene (96 μL, 6.5 equiv.), and bis-(1,5-cyclooctadiene)nickel (205 mg, 6.5 equiv.) to a 100 mL round-bottom flask, add 4 mL of anhydrous DMF thereto, stir at room temperature for 0.5 h. Dissolve monomer TPM-DPP-6Br (160 mg, 0.1144 mmol) in 4 mL of anhydrous DMF and 12 mL of anhydrous THF, react at room temperature for 48 h under nitrogen protection. After the reaction is completed, quench the reaction solution with 10 mL of 11 M hydrochloric acid, stir for 2 h and then filter. Wash the filter cake repeatedly with 50 mL of dichloromethane, 50 mL of tetrahydrofuran, 50 mL of water, and 50 mL of methanol, and dry in vacuo to obtain 100 mg of a yellow solid (yield 94%)

[0116] Example 7

[0117] Synthesis of PAF-PBI (x = 1):

[0118] 2,2'-Bipyridine (112 mg, 6.5 equiv), 1,5-cyclooctadiene (95 μL, 6.5 equiv), and bis-(1,5-cyclooctadiene)nickel (200 mg, 6.5 equiv) were added to a 100 mL round-bottom flask. 10 mL of anhydrous DMF was added thereto, and the mixture was stirred at room temperature for 0.5 h. The monomer TPM-PBI-6Br (180 mg, 0.1099 mmol) was dissolved in 5 mL of anhydrous DMF and 15 mL of anhydrous THF, and the reaction was carried out at room temperature for 48 h. After the reaction was completed, the reaction solution was quenched with 6 mL of 11 M hydrochloric acid, stirred for 2 h, and then filtered. The filter cake was washed repeatedly with 50 mL of dichloromethane, 50 mL of tetrahydrofuran, 50 mL of water, and 50 mL of methanol, and dried under vacuum to obtain 100 mg of a red solid (yield 78%).

[0119] Figure 1 Figure for the sample photos of porous aromatic frameworks PAF-xDPP with different feed ratios in Examples 3-6 under sunlight and 365 nm ultraviolet light. It can be seen from the figure that the prepared PAF-xDPP has a fluorescence response.

[0120] Figure 2 Solid-state NMR of PAF-DPP prepared in Example 6 13 C NMR spectrum, which proves the successful synthesis of PAF-DPP.

[0121] Figure 3 Figure for the UV-visible absorption spectra of solid powders of porous aromatic frameworks PAF-xDPP with different feed ratios in Examples 3-6. It can be seen from the figure that the absorption intensity of PAF-xDPP increases, indicating that the DPP content in the porous aromatic framework increases with the increase of the feed ratio.

[0122] Figure 4 Figure for the thermogravimetric analysis of porous aromatic frameworks PAF-xDPP with different feed ratios in Examples 3-6. It can be seen from the figure that PAF-xDPP has excellent thermal stability.

[0123] Figure 5 Figure for the adsorption efficiency of PAF-5%DPP prepared in Example 3 for crystal violet at 25°C. It can be seen from the figure that PAF-5%DPP can adsorb crystal violet quickly and efficiently.

[0124] Figure 6 Figure for the UV-visible absorption spectrum of the adsorption of crystal violet by PAF-5%DPP prepared in Example 3 in an aqueous solution. It can be seen from the figure that after crystal violet is adsorbed, the absorbance in the aqueous phase decreases rapidly.

[0125] Figure 7 Figure for the UV-visible absorption spectrum of the solid powder of PAF-PBI prepared in Example 7. It can be seen from the figure that it has strong absorption in both the ultraviolet and visible light regions.

[0126] Figure 8 It is a physical picture of the photocatalytic degradation of methylene blue by the PAF-PBI solid powder prepared in Example 7. It can be seen from the figure that after photocatalytic degradation, the methylene blue solution becomes colorless.

[0127] Table 1 is a performance table of the photocatalytic oxidation of sulfide to sulfoxide by the PAF-PBI solid powder prepared in Example 7. The reaction formula is as follows:

[0128]

[0129] It can be obtained from Table 1 that by screening the mass of the polymer PAF-PBI and the light power, it is found that under the condition that other conditions remain the same, the greater the light power, the higher the reaction conversion rate of sulfoxide oxidation. And when the polymer is 2 mg and the light power is only 0.5 W, the best reaction conversion rate is 100%.

[0130] Table 1 Performance table of the photocatalytic oxidation of sulfide to sulfoxide by the PAF-PBI solid powder prepared in Example 7

[0131]

[0132] The above description of the embodiments is to facilitate the understanding and use of the invention by those of ordinary skill in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A porous aromatic framework based on a tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural motif, characterized in that, It is obtained by Yamamoto coupling of a hexabromo-substituted dumbbell-shaped tetraphenylmethane-aromatic imide-tetraphenylmethane structural unit and a tetrabromo-substituted tetraphenylmethane structural unit in different molar ratios. Its structural general formula is: Among them, is an aromatic imide or aromatic lactam; x is the molar ratio of the hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit to the tetrabromo-substituted tetraphenylmethane structural unit, and its value range is: 0 - 1.

2. A porous aromatic framework based on a tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit according to claim 1, characterized in that When the value of x is between 0 and 1, the porous aromatic framework is obtained by carrying out a Yamamoto coupling copolymerization reaction of a hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit and a tetrabromo-substituted tetraphenylmethane structural unit; When the value of x is 1, the porous aromatic framework is prepared by carrying out a Yamamoto coupling homopolymerization reaction of a hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit; When the value of x is 0, the porous aromatic framework is obtained by carrying out a Yamamoto coupling homopolymerization reaction of a tetrabromo-substituted tetraphenylmethane structural unit.

3. A porous aromatic framework based on a tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural motif according to claim 1, characterized in that, The porous aromatic framework simultaneously has optoelectronic functional characteristics, porous material characteristics, and fluorescence characteristics.

4. A porous aromatic framework based on a tetra-phenylmethane-aromatic imide-tetra-phenylmethane dumbbell-shaped structural motif according to claim 1, characterized in that, The aromatic imide includes PMDI, NDI, PBI, DPP, and the porous aromatic framework includes PAF-xPMDI, PAF-xNDI, PAF-xPBI, PAF-xDPP, and their structural formulas are respectively: Wherein, R is a hydrogen atom or a chlorine atom.

5. A porous aromatic framework based on a tetra-phenylmethane-aromatic imide-tetra-phenylmethane dumbbell-shaped structural unit according to claim 1, characterized in that, The hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit includes TPM-PMDI-6Br, TPM-NDI-6Br, TPM-PBI-6Br, or TPM-DPP-6Br, and their structural formulas are respectively as follows: The tetrabromo-substituted tetraphenylmethane structural unit is TPM-4Br, and its structural formula is as follows:

6. The porous aromatic framework based on a tetra-phenylmethane-aromatic imide-tetra-phenylmethane dumbbell-shaped structural motif according to claim 1, characterized in that, The hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit is formed by connecting through an imide bond or a lactam bond by reacting TPM-NH2-3Br with the corresponding aromatic anhydride or aromatic lactone, wherein The synthesis route of TPM-PMDI-6Br is as follows: The synthesis route of TPM-NDI-6Br is as follows: The synthesis route of TPM-PBI-6Br is as follows: The synthesis route of TPM-DPP-6Br is as follows:

7. A method for preparing a porous aromatic framework based on a tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural motif as described in any one of claims 1-6, characterized in that, It includes the following steps: S1: Under anhydrous and anaerobic conditions, dissolve the hexabromo-substituted tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit and the tetrabromo-substituted tetraphenylmethane structural unit in an organic solvent according to the molar ratio x, use bis-(1,5-cyclooctadiene) nickel as a catalyst, and 2,2-bipyridine and 1,5-cyclooctadiene as ligands to carry out a Yamamoto coupling reaction; S2: Quench the reaction with concentrated hydrochloric acid, wash and vacuum dry the obtained product to obtain the porous aromatic framework.

8. The preparation method of a porous aromatic framework based on a tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit according to claim 7, characterized in that In step S1, the anhydrous and anaerobic condition means that the reaction is carried out under the condition of a nitrogen protection atmosphere, the organic solvent is a mixed solvent of N,N-dimethylformamide and tetrahydrofuran, the volume ratio of N,N-dimethylformamide to tetrahydrofuran is 1:2 - 5:1, and the reaction time is 40 - 56 h.

9. The preparation method of a porous aromatic framework based on a tetra-phenylmethane-aromatic imide-tetra-phenylmethane dumbbell-shaped structural unit according to claim 7, characterized in that, In step S2, the concentration of the concentrated hydrochloric acid is 9 - 13 M, the washing means washing successively with dichloromethane, tetrahydrofuran, water and methanol, and the temperature of the vacuum drying is 80 - 120 °C and the time is 20 - 28 h.

10. Use of a porous aromatic framework based on a tetraphenylmethane-aromatic imide-tetraphenylmethane dumbbell-shaped structural unit as described in any one of claims 1-6, characterized in that, Including applications in the fields of adsorption and separation of gases and micro-pollutants, photocatalytic degradation of pollutants and photocatalytic reaction technology.

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