Construction of crystalline supramolecular polymer based on snap ring aromatic hydrocarbon and selective recognition of p-xylene isomer of crystalline supramolecular polymer based on snap ring aromatic hydrocarbon

Abstract

The invention provides a crystalline supramolecular polymer based on snap ring aromatic hydrocarbon. The polymer is obtained by self-assembling snap ring aromatic hydrocarbon (CLP) and a naphthalimide derivative (NDI-8) through a subject and an object. The crystalline supramolecular polymer (NDI-8 (at) CLPalpha) can fully utilize the synergistic effect of a plurality of weak interactions, so that the charge transfer interaction between molecules can be remarkably enhanced very easily. The crystalline supramolecular polymer constructed based on charge transfer shows excellent gasochromic performance. The p-xylene in the NDI-8-coated CLPalpha p-xylene isomer has efficient identification and detection capability, the color is changed from purple to light pink, and a wide application prospect is provided for the development of stimuli-responsive materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials, and particularly relates to a method for constructing a calixarene crystalline supramolecular polymer, and the application of the polymer in the selective recognition of p-xylene in xylene isomers. Background Art

[0002] As an important field of supramolecular chemistry research, host-guest recognition based on macrocyclic hosts has always been a hot topic for supramolecular chemists. Designing new molecular recognition systems based on macrocyclic hosts to meet the needs of the research and development of host-guest chemistry and further enrich the research field of supramolecular chemistry has always been a direction that supramolecular chemists have been working towards. Due to the excellent host-guest recognition properties of macrocyclic host molecules, host-guest recognition systems based on macrocyclic hosts have been developed and applied in many fields. Due to their special cyclic structures and superior host-guest molecular recognition properties, these supramolecular macrocycles have been widely used in supramolecular self-assembly, molecular machines, supramolecular polymers, optical materials, controllable self-assembly nano-drug delivery systems, precise adsorption and separation, etc., reflecting the great research and application value of macrocycle-based molecular recognition in the field of supramolecular chemistry. Especially in the research of supramolecular polymers, it has shown excellent application prospects.

[0003] In modern supramolecular chemistry, novel macrocyclic hosts have become important tools for constructing various molecular assemblies due to their excellent cavities and extensive guest-binding abilities. At present, the research on controllable self-assembly mainly focuses on solution-state supramolecular functional soft materials. How to achieve the controllable self-assembly of crystalline supramolecular functional materials remains one of the scientific problems that need to be solved urgently in the field of self-assembly. Compared with solution-state supramolecular functional soft materials, crystalline supramolecular functional materials have the advantages of higher stability, higher physical strength, better processability, clear material structure-activity relationships, convenient and rapid structure identification, and strong practical applicability. However, the research and application exploration of crystalline supramolecular polymers constructed by charge transfer have not received extensive attention and reports in the past few decades.

[0004] Currently, there are technical problems such as time-consuming and expensive for p-xylene isomer detection materials. Based on this, we propose a crystalline supramolecular polymer material constructed by charge transfer interaction to achieve rapid and intuitive detection of p-xylene in xylene isomers. Summary of the Invention

[0005] The present invention provides a calixarene crystalline supramolecular polymer and a method for constructing the same. The polymer is prepared by the controllable self-assembly of calixarene CLP and naphthalenediimide derivative NDI-8 in the solid state, has excellent gasochromic properties, and realizes the selective recognition of p-xylene in xylene isomers.

[0006] The present invention constructs a crystalline supramolecular polymer based on the host-guest interaction of calix[4]arene, which is obtained by the host-guest self-assembly of calix[4]arene CLP and naphthalene diimide derivative NDI-8; the molar ratio of the calix[4]arene to the naphthalene diimide derivative NDI-8 is 2:1; The structural formula of calix[4]arene (CLP) is: The structural formula of naphthalene diimide derivative NDI-8 is: .

[0007] Among them, the synthesis method of the naphthalene diimide derivative NDI-8: Suspend 1,4,5,8-naphthalenetetracarboxylic dianhydride in dry dimethylformamide, add octylamine, and heat the mixture to 130 °C and stir for 12 hours under N 2 protection. After cooling the mixture to room temperature, filter it under reduced pressure and wash it with distilled water to obtain a pink solid compound NDI-8; the molar ratio of 1,4,5,8-naphthalenetetracarboxylic dianhydride to octylamine is 1:3.

[0008] The construction method of the crystalline supramolecular polymer based on calix[4]arene of the present invention includes the following steps: (1) Mix calix[4]arene (CLP) and naphthalene diimide derivative (NDI-8) according to a molar ratio of 2:1; (2) Dissolve the mixture in dichloromethane (CH 2 Cl 2 ) solution, and then add acetonitrile (CH 3 CN) solution; (3) Through heating-cooling co-crystallization, purple solid crystal powder, namely crystalline supramolecular polymer NDI-8@CLPα, is obtained. The heating temperature of the heating-cooling co-crystallization is 60-70 °C, the heating time is 10 minutes, and the heating-cooling co-crystallization is repeated 3 times under vacuum conditions. A common rotary evaporator in the laboratory can complete it, and the operation is simple.

[0009] The thermal stability test of the crystalline supramolecular polymer NDI-8@CLPα shows that it has good thermal stability below 160 °C. The X-ray powder diffraction (PXRD) pattern of the crystalline supramolecular polymer NDI-8@CLPα matches the pattern simulated by the X-ray single crystal structure. A broad absorption band appears in the solid-state ultraviolet-visible absorption spectrum of the crystalline supramolecular polymer NDI-8@CLPα, indicating the formation of a charge transfer complex. The scanning electron microscope (SEM) image of the crystalline supramolecular polymer NDI-8@CLPα shows that it has a hexahedral block structure.

[0010] The present invention provides an application of a crystalline supramolecular polymer in the selective recognition of xylene isomers, and the supramolecular polymer has a single gasochromic response property to p-xylene among the xylene isomers. By using NDI-8@CLPα, it shows a specific response to p-xylene in xylene (o-xylene, m-xylene, p-xylene): its color changes from purple to light pink, while the responses to o-xylene and m-xylene are not obvious. Therefore, this polymer has high-efficiency recognition and detection capabilities for p-xylene and exhibits significant gasochromic behavior. Specifically, it includes: (1) Exposing the supramolecular polymer NDI-8@CLPα to o-xylene, m-xylene, and p-xylene vapors; (2) Realizing the specific recognition of p-xylene by observing the color change of NDI-8@CLPα, and a gasochromic response occurs in p-xylene vapor, with the color changing from purple to light pink; (3) The absorption intensity of NDI-8@CLPα at 528 nm decreases significantly, indicating a weakened charge transfer effect, thereby achieving the rapid detection of p-xylene.

[0011] The temperature of the gasochromic response is room temperature, the response time is 4 h, the response time is fast and has universality.

[0012] In summary, based on the good crystallinity and electron-rich characteristics of calixarene, a naphthalenediimide derivative (NDI-8) with an electron-deficient system was designed and synthesized. Since both calixarene and NDI-8 contain naphthalene functional groups, a strong π-π stacking interaction can form between them, thereby further constructing a charge-transfer crystalline supramolecular polymer. This crystalline supramolecular polymer can make full use of the synergistic effect of multiple weak interactions, thus very easily achieving a significant enhancement of the intermolecular charge transfer interaction. This crystalline supramolecular polymer constructed based on charge transfer exhibits excellent gasochromic properties. Therefore, we prepared the crystalline supramolecular polymer NDI-8@CLPα (purple), which has high-efficiency recognition and detection capabilities for p-xylene among the xylene isomers and exhibits significant gasochromic behavior, providing a broad application prospect for the development and utilization of stimulus-responsive materials. Description of the Drawings

[0013] Figure 1 1H NMR spectrum of naphthalenediimide derivative NDI-8.

[0014] Figure 2 Crystal structure diagram of NDI-8@CLP.

[0015] Figure 3 PXRD pattern of NDI-8@CLPα.

[0016] Figure 4 Thermogravimetric analysis diagram of NDI-8@CLPα.

[0017] Figure 5 Solid-state ultraviolet-visible spectroscopy diagrams of CLP, NDI-8@CLPα, and NDI-8.

[0018] Figure 6 Density functional theory (DFT) calculations: (a) frontier molecular orbitals of CLP, (b) NDI-8@CLPα, and (c) NDI-8, and the corresponding first energy gap differences.

[0019] Figure 7 SEM image of the NDI-8@CLPα charge transfer complex.

[0020] Figure 8 Analysis of π-π stacking interactions and surface electrostatic potential diagrams shown by the crystal structures of CLP and NDI-8.

[0021] Figure 9 Gasochromic response diagrams of NDI-8@CLPα in the vapors of xylene isomers (o-xylene, m-xylene, p-xylene).

[0022] Figure 10 Solid-state ultraviolet-visible diffuse reflectance spectroscopy diagrams of NDI-8@CLPα adsorbed with o-xylene, m-xylene, and p-xylene vapors, respectively.

[0023] Figure 11 X-ray powder diffraction (PXRD) diagrams of the adsorption and desorption of p-xylene by NDI-8@CLPα.

[0024] Figure 12 1H NMR chemical shift comparisons of (a) p-xylene, (b) NDI-8@CLPα after adsorbing p-xylene, and (c) NDI-8@CLPα. Detailed implementation methods

[0025] The present invention will be described below in conjunction with the example diagrams, aiming to enable those skilled in the art to understand the present invention more clearly, and it is not limited to the scope of use of the present invention.

[0026] Example 1 Construction method of crystalline supramolecular polymer (1) Calix[4]arene (CLP) The calix[4]arene used is an existing material, such as disclosed by Shi et al. in " Journal of the American Chemical Society ", Vol. 146, pp. 2901–2906, 2024.

[0027] (2) Synthesis of naphthalene diimide derivative NDI-8 In a 100 mL round-bottom flask, 1,4,5,8-naphthalenetetracarboxylic dianhydride (0.30 g, 1.12 mmol) was suspended in dry N,N-dimethylformamide (DMF) (50 mL), and octylamine (0.43 g, 3.36 mmol) was added. Under N 2 protection, the mixture was heated to 130 °C and stirred for 12 h. After the mixture was cooled to room temperature, it was filtered under reduced pressure and washed with distilled water to obtain a pink solid compound NDI-8 (0.52 g, 75%). 1 H NMR (400 MHz, Chloroform- d ) δ 8.75 (s, 4H), 4.24 – 4.13 (m, 4H), 1.74 (p, J = 7.5 Hz, 4H), 1.48 – 1.19 (m, 20H), 1.03 – 0.74 (m, 6H). (3) Preparation of crystalline supramolecular polymer NDI-8@CLPα Take CLP (113.3 mg) and NDI-8 (12.25 mg) in a 50 mL round-bottom flask, add 5 mL of CH 2 Cl 2 solution to dissolve, and then add 15 mL of CH 3 CN solution. Heat-cooling co-crystallization was carried out three times (heating temperature was 65 °C and time was 10 minutes) to obtain a purple solid crystal powder, which was NDI-8@CLPα.

[0028] Example 2: Characterization of crystalline supramolecular polymer NDI-8@CLPα Figure 2 is the crystal structure diagram of NDI-8@CLP. From the X-ray powder diffraction (PXRD) experiment of the solid material, it can be seen that the PXRD pattern of NDI-8@CLPα can be well matched with the pattern simulated by the X-ray single crystal structure ( Figure 3 ). At the same time, the thermogravimetric analysis test (TGA) of the solid material shows that NDI-8@CLPα exhibits good thermal stability below 160 °C ( Figure 4 ). A broad absorption band appears in the solid-state ultraviolet-visible absorption spectrum of the NDI-8@CLPα solid material, indicating the formation of a CT complex ( Figure 5 ). The density functional theory (DFT) was used to calculate the relationship between the structure and properties of the macrocyclic co-crystal ( Figure 6), which can indicate the enhancement of CT interaction. The microscopic morphology of the host-guest complex was observed by scanning electron microscopy (SEM). The NDI-8@CLPα solid material presented a hexahedral block structure ( Figure 7 ). The molecular structure of naphthalene is formed by the fusion of two benzene rings through sharing two adjacent carbon atoms, forming a planar conjugated system. The bond between the two carbon atoms shared by the two benzene rings is a double bond. Therefore, naphthalene actually contributes 10 π electrons, and the electrostatic potential map further proves that it contains abundant π electrons. Therefore, the naphthalene groups of the macrocyclic host CLP and the naphthalene groups of the naphthalimide derivative NDI-8 form strong π-π stacking (3.378 Å, 3.313 Å, 3.367 Å, 3.353 Å, 3.382 Å) interactions, and the crystal structure and stacking mode can be well demonstrated ( Figure 8 ).

[0029] Example 3: Gasochromic study of NDI-8@CLPα Gas-phase independent experiments on the efficient capture of xylene vapor by the crystalline supramolecular polymer constructed by calixarene and naphthalimide derivative NDI-8. Before the gasochromic experiment, the crystalline polymer NDI-8@CLPα was heated at 60 °C for 2 h to prevent the influence of surface adsorption on gasochromism. Subsequently, 5.00 mL vials containing 5.00 mg of NDI-8@CLPα were placed in 20.00 mL sealed vials containing 1.00 mL of o-xylene, m-xylene, and p-xylene, respectively. NDI-8@CLPα showed specific response to p-xylene in the xylene isomer vapor: its color changed from purple to light pink, while the response to o-xylene and m-xylene was not obvious ( Figure 9 ). As Figure 10 The solid-state ultraviolet-visible diffuse reflectance spectrum showed that when exposed to p-xylene vapor, the absorption intensity of the material at 528 nm decreased significantly, indicating the weakening of charge transfer interaction. Therefore, the selective gas-phase color-changing sensing ability of NDI-8@CLPα as these substrates was confirmed. Through further analysis of the crystalline supramolecular polymer, the results showed that obvious changes occurred in the PXRD pattern ( Figure 11 ) after adsorption of p-xylene. Subsequently, by vacuum heating the adsorbed solid powder, the PXRD pattern was basically consistent with the crystal simulation diagram of NDI-8@CLPα. Therefore, multiple cyclic detections of p-xylene vapor can be realized. In addition, 1 1H NMR spectra of the crystalline supramolecular polymer NDI-8@CLPα, p-xylene, and NDI-8@CLPα after adsorption of p-xylene were carried out ( Figure 12)Analysis results show that when p-xylene is adsorbed, the H protons of NDI-8 exhibit a significant downfield shift, while the H protons on p-xylene show a significant upfield shift, indicating that the host-guest interaction between CLP and NDI-8 has changed and p-xylene has entered the cavity of CLP. These results provide strong evidence for the adsorption mechanism of p-xylene.

Claims

1. A crystalline supramolecular polymer based on carbocyclic aromatic hydrocarbons, characterized in that: The supramolecular polymer is obtained by host-guest self-assembly of carbocyclic aromatic hydrocarbon CLP and naphthalene diimide derivative NDI-8; The structural formula of carbocyclic aromatic hydrocarbons CLP is: The structural formula of naphthalene diimide derivative NDI-8 is: 。 2. The crystalline supramolecular polymer based on carbocyclic aromatic hydrocarbons according to claim 1, characterized in that: The molar ratio of the carbocyclic aromatic hydrocarbon to the naphthalene diimide derivative NDI-8 is 2:

1.

3. The crystalline supramolecular polymer based on carbocyclic aromatic hydrocarbons according to claim 1, characterized in that: The synthesis method of the naphthalene diimide derivative NDI-8 is as follows: 1,4,5,8-naphthalenetetracarboxylic anhydride is suspended in dry dimethylformamide, octylamine is added, the mixture is heated to 120-140° C. under N2 protection and stirred for 10-15 hours, the mixture is cooled to room temperature, filtered under reduced pressure, and washed with distilled water to obtain a pink solid compound NDI-8.

4. The carbocyclic aromatic hydrocarbon-based crystalline supramolecular polymer according to claim 3, characterized in that: The molar ratio of 1,4,5,8-naphthalenetetracarboxylic anhydride to octylamine is 1:

3.

5. The method for constructing a crystalline supramolecular polymer based on carbocyclic aromatic hydrocarbons according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Carbocyclic aromatic hydrocarbon (CLP) and naphthalene diimide derivative (NDI-8) were mixed in a molar ratio of 2:1; (2) Dissolve the mixture in dichloromethane (CH2Cl2) solution, and then add acetonitrile (CH3CN) solution; (3) After heating-cooling co-crystallization, a purple solid crystalline powder was obtained, namely, the crystalline supramolecular polymer NDI-8@CLPα.

6. An application of the crystalline supramolecular polymer according to claim 1 in the selective recognition of xylene isomers, characterized in that: The p-xylene in the supramolecular polymer p-xylene isomer has a single gas-induced chromic response property.

7. Use of the crystalline supramolecular polymer according to claim 6 in the selective recognition of xylene isomers, characterized in that: The activated supramolecular polymer NDI-8@CLPα was exposed to o-, m-, and p-xylene vapors. The specific recognition of p-xylene among the xylene isomers was achieved by observing the color change of NDI-8@CLPα, whose color changed from purple to light pink, while the response to o-xylene and m-xylene was not obvious.

8. Use of the crystalline supramolecular polymer according to claim 7 in the selective recognition of xylene isomers, characterized in that: The gas-induced chromic response temperature is room temperature and the response time is 4 h.

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