A class of pillararene-based polymer materials, their preparation methods and applications

Abstract

The present invention is applicable to the technical field of organic photocatalysts, and provides a novel pillararene-based polymer material, a preparation method thereof and an application. By introducing the supramolecular macrocycle pillararene as a building unit, the present invention designs and prepares a metal-free organic catalyst polymer material TpAP[n] with semiconductor characteristics, which is synthesized by Schiff base condensation reaction. Its unique interlayer ordered stacking restricts the recombination of carriers, forms an effective electron-hole transport path, and provides more active sites, which is beneficial to the efficient contact between reactants and catalytic centers. Experimental results show that this material can significantly improve the production rate of H2O2 under light illumination, demonstrating excellent photocatalytic performance. Moreover, the preparation process is environmentally friendly and conforms to the principles of green chemistry, providing support and theoretical basis for the design and preparation of subsequent series of metal-free organic catalysts.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic photocatalysts, and particularly relates to a class of pillararene-based polymer materials, a preparation method thereof, and an application thereof. Background Art

[0002] As an environmentally friendly and efficient oxidant, hydrogen peroxide (H 2 O 2 ) has been widely used in the fields of organic synthesis, wastewater treatment, disinfection, and pulp and paper making. Currently, the most commonly used method for preparing H 2 O 2 is the anthraquinone method, which involves multiple steps. First, phenol reacts with an excess of acetone to form bis(α-phenylmethyl)cyclohexanone. Then, bis(α-phenylmethyl)cyclohexanone and anthraquinone undergo a series of complex oxidation reactions in the air, ultimately producing H 2 O 2 and CO 2 . However, the preparation process of this method is complex, including multiple reaction and separation steps, with cumbersome operations and long time consumption, resulting in low production efficiency and high costs. Secondly, the anthraquinone method often requires a large amount of energy input. These reactions usually need to be carried out under high temperature and high pressure conditions to promote the reaction rate and yield, leading to a large amount of energy consumption and exacerbating the problem of energy resource scarcity. In addition, a large amount of wastewater is usually generated during the preparation of H 2 O 2 by traditional methods. The wastewater contains unreacted raw materials, intermediate products, and catalyst residues, and requires a complex treatment and purification process to meet the discharge standards, which not only puts pressure on the environment but also increases the economic burden. At the same time, a large number of by-products are generated during this process, resulting in waste of resources and low energy utilization efficiency. To overcome the above problems, the present invention proposes a class of pillararene-based polymer materials, a preparation method thereof, and an application thereof. Summary of the Invention

[0003] The purpose of the present invention is to provide a class of pillararene-based polymer materials, a preparation method thereof, and an application thereof, aiming to solve the problems raised in the above background art.

[0004] To achieve the above purpose, the present invention provides the following technical solutions:

[0005] A preparation method of a class of pillararene-based polymer materials, and the synthesis route of the polymer material TpAP[n] is as follows:

[0006] ;

[0007] Wherein:

[0008] ;

[0009] 。

[0010] Further, when the structural formula of the polymer material donor is as follows, the polymer material TpAP[5] is prepared;

[0011] ;

[0012] The preparation steps of the polymer material TpAP[5] are as follows:

[0013] Weigh 26.2 mg of the donor molecule aniline-functionalized pillar[5]arene and 4.2 mg of the acceptor molecule phloroglucinol trialdehyde, add them to a 10 mL Schlenk tube, then add 2 mL of a mixed solution of 1,4-dioxane and mesitylene to the Schlenk tube, perform ultrasonic treatment until evenly mixed, add 100 μL of 6 mol / L acetic acid solution, and mix evenly; use a double-tube to perform 3 gas exchanges on the air in the Schlenk tube to fill the bottle with nitrogen; place the Schlenk tube in an oven at 120 °C and react for 72 h to obtain a yellow powdery solid, wash it with tetrahydrofuran and then dry it to obtain the polymer material TpAP[5].

[0014] A pillararene-based polymer material prepared by the preparation method of the pillararene-based polymer material described above.

[0015] An application of a pillararene-based polymer material prepared by the preparation method of the pillararene-based polymer material described above in photocatalytic production of H 2 O 2 2

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] In the present invention, by introducing supramolecular macrocyclic pillararenes as building units, a metal-free organic catalyst polymer material TpAP[5] with semiconductor characteristics is designed and prepared, which is synthesized by Schiff base condensation reaction. Its unique interlayer ordered stacking restricts the recombination of carriers, forms an effective electron-hole transport path, and provides more active sites, which is beneficial to the efficient contact between reactants and catalytic centers. Experimental results show that this material can significantly improve the production rate of H 2 O 2 2 Description of the Drawings

[0018] Figure 1Characterization diagrams of the physical and chemical properties of TpAP[5]; among them, (a) is the thermogravimetric curve diagram of TpAP[5]; (b) is the scanning electron microscope diagram of TpAP[5]; (c) is the X-ray photoelectron spectroscopy diagram of TpAP[5]; (d) is the infrared spectroscopy diagram of TpAP[5].

[0019] Figure 2 For the standard curve diagram of H 2 O 2 produced by TpAP[5].

[0020] Figure 3 For the ultraviolet absorption spectrum diagram of H 2 O 2 produced by detecting TpAP[5] by the iodometric method.

[0021] Figure 4 Characterization diagrams of the performance and properties of TpAP[5]; among them, (a) is the electrochemical impedance spectrum diagram of TpAP[5]; (b) is the photocurrent spectrum diagram of TpAP[5]; (c) is the photocatalytic H 2 O 2 production rate diagram of TpAP[5] and TpDT; (d) is the electron paramagnetic resonance spectrum diagram of TpAP[5]. Specific implementation manners

[0022] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] The following describes the specific implementation of the present invention in detail in conjunction with specific embodiments.

[0024] Example 1: Prepare a polymer material TpAP[5] using aniline-modified pillar[5]arene as a building unit;

[0025] Weigh 26.2 mg of aniline-functionalized pillar[5]arene (abbreviated as APP[5]) and 4.2 mg of phloroglucinol trialdehyde (abbreviated as Tp) into a 10 mL Schlenk tube. These two reactants will undergo polymerization through a Schiff base condensation reaction. Add 2 mL of a mixed solution of 1,4-dioxane and mesitylene to the Schlenk tube, perform ultrasonic treatment until evenly mixed, add 100 μL of 6 mol / L acetic acid solution, and mix evenly. Use a double-row tube to perform 3 gas exchanges on the air in the Schlenk tube to fill the bottle with nitrogen. Place the Schlenk tube in an oven at 120 °C and react for 72 h to obtain a yellow powdery solid. After washing it with tetrahydrofuran multiple times and drying it, obtain the polymer material TpAP[5].

[0026] The synthetic route of the polymer material TpAP[5] is as follows:

[0027] ;

[0028] Among them:

[0029] ;

[0030] .

[0031] As Figure 1 shown in (a)-(d) below, different characterization methods were used to prove the successful preparation and properties of the polymer material TpAP[5]. Specifically, as can be seen from Figure 1 (a) below, obvious mass loss of TpAP[5] began at 390 °C, and 62% of the mass remained at 900 °C, indicating that the material had good thermal stability. Figure 1 (b) below shows the microscopic morphology of TpAP[5] observed by scanning electron microscopy, and it can be seen that it is basically spherical. It should be noted that the interlayer ordered stacking of TpAP[5] not only restricted the recombination of carriers, but also formed an effective electron-hole transport path and provided more active sites, which was beneficial to the efficient contact between reactants and catalytic centers. In addition, the carbon, nitrogen, and oxygen elements that make up the main body of the material were also shown in the X-ray photoelectron spectroscopy diagram, as shown in detail in Figure 1 (c) below. As Figure 1 (d) below shows, the infrared spectrum compared the characteristic peaks of the polymer material TpAP[5] and the monomer. With the disappearance of the amino peak position and the formation of carbon-carbon double bonds, it can be determined that the polymerization of TpAP[5] was successful.

[0032] Example 2: Construction of a photocatalytic H 2 O 2 production catalytic system based on TpAP[5];

[0033] The catalyst was mixed with deionized water in a certain ratio (1:5 - 1:10) to prepare a suspension (sacrificial agents, including but not limited to organic substances such as ethanol, could also be added to the solution to promote electron transfer, thereby improving the production efficiency of H 2 O 2 ). Oxygen was introduced into the reaction system for 40 - 60 min to make the suspension in an oxygen-rich environment, and it was stirred until adsorption equilibrium under airtight and light-free conditions. A visible light source was introduced, the temperature of the system was controlled to remain at room temperature, a fixed amount (1 - 3 mL) of the reaction solution was extracted every 10 min, and the catalyst material was removed by centrifugation. Then, 1 mL of 0.1 mol / L C 8 H 5 O 4The K solution and 1 mL of 0.4 mol / L potassium iodide (KI) solution were thoroughly mixed. Since H 2 O 2 can oxidize I - in the KI solution into free iodine, and the free iodine will react with the remaining I - to form I 3 - , which is detected at a specific wavelength (such as 352 nm). After reacting for 30 min, the corresponding absorption value of I 3 - was monitored by ultraviolet spectroscopy. As Figure 2 shown, the relationship between the absorbance and concentration calculated by the Lambert-Beer law can be used to establish a standard curve. As Figure 3 shown, by measuring the absorbance value of the reaction solution at 352 nm, substituting it into the obtained standard curve and performing the corresponding concentration conversion, the change in the concentration of I 3 - can be monitored in real time, and then the concentration of H 2 O 2 and its generation rate can be deduced.

[0034] Example 3: A control experiment on the influence of whether the catalyst has a pillararene structure on the catalytic rate;

[0035] The results are as shown in (a) and (b) of Figure 4 . TpAP[5] shows a smaller impedance and better photocurrent responsiveness than the control material (formed by polymerizing 4,4''-diaminotriphenyl and phloroglucinol trialdehyde, TpDT), indicating that TpAP[5] has relatively higher photocatalytic potential. Under the same reaction conditions, the material TpAP[5] with a pillararene structure and the control material were tested. The results are as shown in (c) of Figure 4 . TpAP[5] shows an obvious rate advantage (2343 μmol g⁻¹ h⁻¹), which is 2 times that of the control material (1083 μmol g⁻¹ h⁻¹), and the catalytic efficiency remains basically unchanged after multiple (3 times) cycles. In addition, as shown in (d) of Figure 4 , four characteristic peaks are shown in the electron paramagnetic resonance spectrum of TpAP[5], indicating that the signature reactive oxygen species superoxide radical in this photocatalytic process is detected, which is convenient for exploring the factors affecting the rate-determining step to optimize the performance of subsequent series of materials.

[0036] The above are only the preferred embodiments of the present invention. It should be noted that for those skilled in the art, without departing from the concept of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicability of the patent.

Claims

1. A polymer material TpAP[5], characterized in that: The synthesis route of the polymer material TpAP[5] is as follows: ； in: ； ； The preparation steps of the polymer material TpAP[5] are as follows: 26.2 mg of donor molecule aniline functionalized column [5] aromatic hydrocarbon and 4.2 mg of acceptor molecule trialdehyde pyrogallol were weighed and added to a 10 mL Shrek tube. Then, 2 mL of a mixed solution of 1,4-dioxane and mesitylene was added to the Shrek tube and ultrasonically treated until mixed evenly. 100 μL of 6 mol / L acetic acid solution was added and mixed evenly. The air in the Shrek tube was exchanged three times using a double-row tube to fill the bottle with nitrogen. The Shrek tube was placed in an oven at 120°C for reaction for 72 h to obtain a yellow powdery solid, which was washed with tetrahydrofuran and dried to obtain the polymer material TpAP [5].

2. Use of the polymer material TpAP[5] according to claim 1 in photocatalytic production of H2O2.

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