A supramolecular polymer photocatalyst based on pillararene

Abstract

The present invention discloses a supramolecular polymer photocatalyst based on pillar aromatic hydrocarbons. The supramolecular polymer photocatalyst comprises a compound P5 based on pillar aromatic hydrocarbons and a guest G M Self-assembly can be used to catalyze the reduction reaction of p-nitrophenol under the condition of xenon lamp illumination. In the present invention, a supramolecular polymer is formed by self-assembly based on pillar aromatics and guests. Since the oxygen atoms on the π-π stacked ester groups of the guests are the binding sites of hydrogen atoms, under the irradiation of Xe-lamp, the electrons are excited, and the supramolecular polymer can better transfer electrons, thereby improving the catalytic efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of organic polymer materials, and in particular relates to a supramolecular polymer based on pillar aromatics and an application thereof in preparing a photocatalyst. Background Art

[0002] In the past decade, the combination of photocatalysis and organic catalysis has made remarkable progress in modern chemical synthesis. In this dual catalytic system, the photocatalyst or photosensitizer absorbs visible light to induce its photoexcited state, activates the unreactive substrate through electron or energy transfer mechanism, and usually uses organic catalyst to adjust the chemical reactivity of its substrate. At present, most research work focuses on environmental governance and improvement such as degradation of pollutants in water and air, and electrochemical processes such as conversion of light energy and interfacial electron transfer. Despite this, the use of photocatalysis in the synthesis of specific organic compounds has gained increasing attention. As we all know, traditional organic synthesis is not only cumbersome, but also the catalysts used are usually toxic or corrosive. Photocatalytic reaction introduces sunlight into the organic synthesis system, which is undoubtedly a major breakthrough from the perspective of environmental protection. Pillar aromatics are the latest class of macrocyclic host compounds. They are a class of highly symmetrical oligomeric columnar compounds obtained by hydroquinone ethers and their derivatives, connected by methylene bridges at the 2,5-position. Compared with crown ethers and calixarene, pillararene has a more rigid structure and better symmetry. Compared with cycloalkanes and cucurbiturils, pillararene is easier to functionalize. Pillararene can not only complex with cationic and anionic guests, but also with neutral guests, which makes it easy to construct supramolecular polymers.

[0003] The invention designs and utilizes the host-guest complexation between pillar aromatics and cationic guests to construct a novel supramolecular polymer based on pillar aromatics and uses it for organic catalysis and photocatalysis. Summary of the invention

[0004] The purpose of the present invention is to provide a supramolecular polymer based on pillararene and application thereof in preparing a photocatalyst.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A pillararene-based supramolecular polymer comprising a pillararene-based compound P5 and a guest G M Self-assembly formation,

[0007] The structural formula of the compound P5 is shown below:

[0008]

[0009] The object G M The structural formula is shown below:

[0010]

[0011] The method for preparing the supramolecular polymer is as follows: Compound P5 is added to chloroform, and then guest G is added M , stirred and dissolved to obtain a supramolecular polymer.

[0012] Application of the supramolecular polymer in the preparation of photocatalysts.

[0013] Furthermore, the photocatalyst is used to catalyze the reduction reaction of p-nitrophenol under the illumination of a xenon lamp.

[0014] In the present invention, a supramolecular polymer is formed based on the self-assembly of pillar aromatics and guests. Since the oxygen atoms on the π-π stacked ester groups of the guests are the binding sites of hydrogen atoms, under the irradiation of Xe-lamp, electrons are excited and the supramolecular polymer can better transfer electrons, thereby improving the catalytic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 NMR spectra of compound P5 (a) and compound PTP (b).

[0016] Figure 2 This is a scanning electron micrograph of a supramolecular polymer.

[0017] Figure 3 For p-nitrophenol in compound P5, guest G M and time-varying UV results in the presence of supramolecular polymers. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with the accompanying drawings and specific examples, but it should not be construed as limiting the present invention. Without departing from the spirit and substance of the present invention, the modification or replacement of the method, steps or conditions of the present invention all belong to the scope of the present invention. The experimental methods and reagents without specifying the specific conditions in the examples are all in accordance with the conventional conditions in the art.

[0019] Example 1 Preparation of Pillararene-based Supramolecular Polymer Catalyst

[0020] 1. Preparation of pillar aromatics PTP

[0021]

[0022] Synthesis of pillar aromatic hydrocarbon PTP: In a 50 mL round-bottom flask, pillar aromatic hydrocarbon (P1) (1 mmol, 0.916 g), terpyridine (TP) (1.05 mmol, 0.343 g) and K2CO3 (5 mmol. about 0.693 g) were weighed and dissolved in 25 mL acetonitrile. The reaction system was heated under reflux for 8 h under magnetic stirring, and the reaction progress was monitored by TCL. After the reaction was completed, the system was concentrated and the crude product was separated by column chromatography (DCM: MeOH = 25: 1). A light yellow solid PTP was obtained.

[0023] PTP: light yellow solid, 83%, mp℃; 1 H NMR(400MHz,Chloroform-d)δ8.76(d,J=4.1Hz,4H),8.71(d,J=8.0Hz,2H),7.91(d,J=8.1Hz,4 H),7.42–7.37(m,2H),7.03(d,J=8.7Hz,2H),6.82–6.74(m,10H),4.09(t,J=5.9Hz,2H),3.92(t ,J=5.8Hz,2H),3.84(d,J=6.4Hz,2H),3.82–3.74(m,10H),3.69–3.60(m,24H),2.07–1.96(m,4 H),1.78–1.70(m,2H),1.54–1.46(m,2H),0.95(t,J=7.4Hz,3H).MS(m / z):HRMS(ESI)Calcd.for C 72 H 76 N3O 11 ([M+H]+):1158.5480,found:1158.5470.

[0024] PTP (1 mmol, 1.170 g) and ZnCl2 (1.05 mM, 0.069 g) were weighed into a 50 mL round-bottom flask, dissolved in 25 mL of ethanol, heated under reflux for 8 h, cooled and crystallized, and filtered to obtain P5.

[0025] like Figure 1 As shown, from the NMR comparison of P5 and PTPTP, it can be seen that the chemical shifts of the corresponding hydrogens of the two have changed accordingly, indicating that Zn has successfully coordinated with TP to obtain compound P5.

[0026] 2. Preparation of guest cations

[0027]

[0028] In a 50 mL round-bottom flask, 0.125 mmol (0.100 g) of G1 and 6 mL of trimethylamine (30% trimethylamine in ethanol) were dissolved in 10 mL of toluene. The reaction system was heated under reflux for 24 h under magnetic stirring. After the reaction was completed, the system was concentrated, dissolved with a small amount of methanol, precipitated in a large amount of ethyl acetate, and filtered to obtain a white solid.

[0029] 3. Preparation of pillararomatic supramolecular polymer catalysts

[0030] In a 1.5 mL EP tube, add 0.0123 g (0.005 mmol) of compound P5 and 500 μL of chloroform. Add guest G under stirring. M 0.0046 g (0.005 mmol), continue stirring until dissolved, and dry at 60 ° C to obtain a supramolecular polymer catalyst

[0031] like Figure 2 The SEM results show that the formation of fibrous nanorods indicates that P5 and G M Self-assembly formed supramolecular polymers.

[0032] Example 2

[0033] Test of catalytic effect of supramolecular polymer catalyst

[0034] Add 50 μM p-nitrophenol solution to a 5 mL glass bottle and add 1 mg of and G M , under xenon light illumination and magnetic stirring, centrifuge it for 5 minutes at a certain interval, take the supernatant to measure its ultraviolet absorption, then recover it and continue to illuminate and stir. The above experiment was repeated three times. Table 1 is a comparison of the catalytic effect and catalytic rate based on supramolecular polymers and precursor guests.

[0035] Table 1

[0036]

[0037] Reaction conditions: reaction at room temperature under Xe-Lamp irradiation.

[0038] like Figure 3 , respectively at room temperature with P5, G M and As a catalyst, 50 μM p-nitrophenol was catalyzed under xenon light. Its UV absorption was measured under xenon light for the same period of time. It was found that there was no change in UV absorption when P5 was used as a catalyst for 0min, 15min, 20min and 25min of illumination; MWhen the catalyst was illuminated for 0min and 15min, the UV absorption intensity at 15min was lower than that at 0min, indicating that the p-nitrophenol in the solution was consumed. However, when the illumination was continued for 20min and 25min, there was no change in the UV absorption. When the catalyst was illuminated for 0min and 15min, it was found that the UV absorption intensity at 15min was significantly lower than that at 0min, indicating that a large amount of p-nitrophenol in the solution was consumed. When the illumination was continued for 20min and 25min, the UV absorption was slightly reduced and the catalytic rate slowed down. By comparison, it can be seen that the catalytic effect of the p-nitrophenol reduction reaction catalyzed by the prepared new supramolecular polymer catalyst was tested, and it was found that this type of catalyst not only has good catalytic efficiency, but also has a fast catalytic rate.

Claims

1. A supramolecular polymer based on pillararenes, characterized in that: The pillararene-based compound P5 and guest G M Self-assembly formation, The structural formula of the compound P5 is shown below: The object G M The structural formula is shown below:

2. The method for preparing the supramolecular polymer according to claim 1, characterized in that: Compound P5 was added to chloroform, and then guest G was added M , stirred and dissolved to obtain a supramolecular polymer.

3. Use of the supramolecular polymer according to claim 1 in the preparation of photocatalysts.

4. The use according to claim 3, characterized in that: The photocatalyst is used for catalyzing the reduction reaction of p-nitrophenol under the illumination of a xenon lamp.

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