Synthesis method of boron cluster-cucurbituril-triazine unit three-component supramolecular reversible photochromic material

Abstract

The invention provides a synthesis method of a boron cluster-cucurbituril-triazine unit three-component supramolecular reversible photochromic material, which is characterized in that an electron donor boron cluster is directly introduced into a cucurbituril cavity encapsulated with an electron acceptor 2, 4, 6-tri (4-pyridine)-1, 3, 5-triazine in a subject-object self-assembly manner. According to the material, the characteristics that a boron cluster is rich in electrons and negative charges are distributed in a delocalization mode are used as electron donors, convenience is provided for charge transfer between the boron cluster and 2, 4, 6-tri (4-pyridine)-1, 3, 5-triazine by means of a cucurbituril cavity, and photochromism is achieved. Under the irradiation of ultraviolet light, the material is subjected to electron transfer and evolves from creamy white to green, the color can be recovered after the ultraviolet light is removed, and good photochromic performance and fatigue resistance are shown. The supramolecular light-induced reversible color-changing material prepared by the invention is a powdery solid, and the preparation method is simple to operate, reliable in process, good in repeatability and easy for large-scale preparation.

Description

Technical Field

[0001] The present invention relates to a preparation method of a photochromic material, belonging to the field of preparation of intelligent materials, and specifically to a synthesis method of a three-component supramolecular photoinduced reversible color-changing material composed of a boron cluster - cucurbituril - triazine unit. Background Technique

[0002] Supramolecular photoinduced reversible color-changing materials have attracted much attention due to their wide application prospects in the fields of intelligent display, anti-counterfeiting, information encryption, and military camouflage. Traditional photochromic materials have problems such as irreversible color-changing processes, limited color ranges, and poor structural stability. Supramolecular chemistry constructs stable structures through host-guest interactions and non-covalent bonds, providing new ideas for solving these problems. In recent years, researchers have made remarkable progress in material design and synthesis, color-changing mechanism research, performance optimization, and multi-functional integration. Currently, the main methods for synthesizing photochromic materials by hydrothermal method directly, reversible photochromic materials by high-temperature solid-phase method, supramolecular reversible photochromic materials by mechanical grinding method, and supramolecular reversible photochromic materials by layer-by-layer self-assembly method are mainstream methods and are widely participated by researchers. Even so, most of the preparation methods of supramolecular photoinduced reversible color-changing materials developed in the academic community at the present stage have not been promoted to industrial applications. The main reasons include: (1) The material has a large volume change, unstable and irreversible structure during the photochromic process, and a limited color range, and it is impossible to achieve full-color gamut color change; (2) The preparation method is complex and difficult to scale up production. For example, the layer-by-layer self-assembly method requires multiple steps of operation, and the mechanical grinding method results in unstable performance; (3) The equipment and raw material costs are high, the synthesis yield is low, resulting in too high production costs; (4) The application fields are limited, the market scale is small, and the market acceptance is low. Therefore, continuing to develop new technologies for preparing supramolecular reversible photochromic materials is crucial for promoting the development of supramolecular reversible photochromic materials and for industrial applications. Summary of the Invention

[0003] The technical problem solved by the present invention is that by encapsulating the electron acceptor 2,4,6-tris(4-pyridyl)-1,3,5-triazine in the cavity of cucurbituril and then combining it with a boron cluster to form a three-component supramolecular photoinduced reversible color-changing material, the photochromic material created by the present invention can change from off-white to green under ultraviolet light excitation, and after the removal of ultraviolet excitation, the green color of the photochromic material can slowly fade, having excellent photochromic sensitivity and fatigue resistance.

[0004] The specific technical solution adopted by the present invention is as follows:

[0005] A method for directly introducing a boron cluster into cucurbituril loaded with 2,4,6-tris(4-pyridyl)-1,3,5-triazine to prepare a three-component supramolecular photoinduced reversible color-changing material, comprising the following steps:

[0006] A. Encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine into the cavity of cucurbituril: Dissolve 2,4,6-tris(4-pyridyl)-1,3,5-triazine in hydrochloric acid solution, then add cucurbituril dissolved in hydrochloric acid solution, and stir for 12 hours under reflux at 120 °C to obtain a cucurbituril solution encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine;

[0007] B. Constructing a three-component supramolecular material by binding a boron cluster and cucurbituril encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine through supramolecular self-assembly: Add an aqueous solution of the boron cluster to the cucurbituril solution encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine obtained in step A, continuously stir to allow the boron cluster and cucurbituril to fully bind, filter and separate the solid, and dry it to obtain a supramolecular photoinduced reversible color-changing material composed of three components: 2,4,6-tris(4-pyridyl)-1,3,5-triazine, cucurbituril, and the boron cluster.

[0008] In step A, the cucurbituril is cucurbituril[7] (CB[7]).

[0009] In step A, the concentration of the hydrochloric acid solution is 1 mol / L.

[0010] Specific implementation of step A: Weigh 1163.0 mg (1.0 mmol) of CB[7] and dissolve it in 40 mL of 1 mol / L hydrochloric acid solution to form solution A; dissolve 203.1 mg (0.33 mmol) of TPT in 40 mL of 1 mol / L hydrochloric acid solution to form solution B; mix solution A and solution B in a 250 mL round-bottom flask, transfer the round-bottom flask to an oil bath at 80 °C, and under reflux, continuously react for 12 hours and then cool the reaction solution to room temperature to obtain a cucurbituril solution encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine.

[0011] In step B, the boron cluster is the dodecahydrododecaborate anion, and the cation of the borane cluster can be cesium ion (Cs + ), potassium ion (K + ), sodium ion (Na + ), lithium ion (Li + ).

[0012] In step B, the duration of continuous stirring can be from 2 minutes to 1 hour.

[0013] Specific implementation of step B is: Weigh 203.8 mg (0.5 mmol) of Cs2(B 12 H 12 )(Cs + is cesium ion, [B 12 H12 2- Dissolve 12 (dodecahydrododecaborate cluster anion) in 40 mL of ultrapure water; subsequently, add the above solution to the cucurbituril solution encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine under stirring conditions; after reacting for 1 hour, separate the solid by suction filtration, wash the filter cake 3 times with ultrapure water, and then dry the solid at 80 °C for 6 hours to obtain the supramolecular photoinduced reversible color-changing material composed of 2,4,6-tris(4-pyridyl)-1,3,5-triazine, cucurbituril, and boron cluster as three components.

[0014] The present invention provides a method for preparing a supramolecular photoinduced reversible color-changing material by directly introducing an electron donor boron cluster into cucurbituril encapsulating an electron acceptor 2,4,6-tris(4-pyridyl)-1,3,5-triazine, obtained according to the above preparation method. The boron cluster and cucurbituril encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine are used to prepare the supramolecular photoinduced reversible color-changing material by a self-assembly method. The boron cluster, which is rich in electrons and has a delocalized negative charge distribution, can act as an electron donor, and 2,4,6-tris(4-pyridyl)-1,3,5-triazine encapsulated by cucurbituril serves as an electron acceptor, realizing the reversible photoinduced color change of the material from white to green under ultraviolet light excitation; by introducing the electron acceptor 2,4,6-tris(4-pyridyl)-1,3,5-triazine into the cucurbituril cavity, cucurbituril can, on the one hand, combine with the boron cluster through host-guest interaction to form a supramolecule. After binding 2,4,6-tris(4-pyridyl)-1,3,5-triazine, it forms an electron acceptor together with cucurbituril, establishing an electron transfer channel with the boron cluster. The supramolecular photoinduced reversible color-changing material is a powdery solid. In the present invention, by directly binding the electron donor boron cluster to cucurbituril encapsulating an electron acceptor, the constructed three-component supramolecular material undergoes electron transfer under ultraviolet light excitation, realizing the photoinduced color change from white to green; after removing the ultraviolet light, the green slowly returns to off-white, which is a brand-new light-reversible color-changing material. The method of the present invention is simple to operate, the preparation process is reliable and has good repeatability, which is conducive to large-scale preparation. Description of the Drawings

[0015] Figure 1 It is the color change image of the PCB-1 supramolecular material before and after ultraviolet light irradiation;

[0016] Figure 2 It is the color change image of the PCB-2 supramolecular material before and after ultraviolet light irradiation. Detailed Embodiments

[0017] The following presents the specific operations of the present invention in combination with examples.

[0018]

Example 1

[0019] ​A method for synthesizing a three-component supramolecular photoinduced reversible color-changing material composed of a boron cluster, cucurbituril, and a triazine unit, comprising the following steps:

[0020] Weigh 1163.0 mg (1.0 mmol) of CB[7] and dissolve it in 40 mL of 1 mol / L hydrochloric acid solution to form solution A; dissolve 203.1 mg (0.33 mmol) of 2,4,6-tris(4-pyridyl)-1,3,5-triazine in 40 mL of 1 mol / L hydrochloric acid solution to form solution B; mix solution A and solution B in a 250 mL round-bottom flask, and transfer the round-bottom flask to an 80 °C oil bath for continuous reflux reaction for 12 hours. Cool the reaction solution to room temperature to obtain a cucurbituril solution encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine; weigh 203.8 mg (0.5 mmol) of Cs2[B 12 H 12 and dissolve it in 40 mL of ultrapure water. Subsequently, add the above solution to the cucurbituril solution encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine under stirring conditions. After continuous reaction for 1 hour, separate the solid by suction filtration, wash the filter cake 3 times with ultrapure water, and dry the solid at 80 °C for 6 hours to obtain a supramolecular photoinduced reversible color-changing material composed of 2,4,6-tris(4-pyridyl)-1,3,5-triazine, cucurbituril, and boron cluster three components, named PCB-1.

[0021] Characterization results of the product obtained in Example 1:

[0022] Figure 1 Figure showing the changes of the powdery boron cluster supramolecular photoinduced reversible color-changing material obtained in Example 1 before and after ultraviolet light irradiation. The results show that the prepared material is a off-white powdery solid, which turns green after ultraviolet light irradiation. After removing the ultraviolet light, the color gradually returns to the original color. The results indicate that the supramolecular material constructed by 2,4,6-tris(4-pyridyl)-1,3,5-triazine, cucurbituril, and boron cluster three components has photoinduced reversible color-changing performance.

[0023]

Example 2

[0024] Weigh 348.9 mg (0.3 mmol) of CB[7] and dissolve it in 40 mL of 1 mol / L hydrochloric acid solution to form solution A; weigh 62.5 mg (0.2 mmol) of 2,4,6-tris(4-pyridyl)-1,3,5-triazine and dissolve it in 40 mL of 1 mol / L hydrochloric acid solution to form solution B. Mix solution A and solution B in a 250 mL round-bottom flask, and transfer the round-bottom flask to an 80 °C oil bath for continuous reflux reaction for 12 hours. Cool the reaction solution to room temperature to obtain a cucurbituril solution encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine; weigh 122.3 mg (0.3 mmol) of Cs2[B 12 H 12 and dissolve it in 40 mL of ultrapure water. Subsequently, add the above solution to the cucurbituril solution encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine under stirring conditions. After continuous reaction for 1 hour, separate the solid by suction filtration, and wash the filter cake 3 times with ultrapure water, and dry it in a blast dryer at 80 °C for 6 hours to obtain a supramolecular photoinduced reversible color-changing material composed of three components: 2,4,6-tris(4-pyridyl)-1,3,5-triazine, cucurbituril, and boron cluster, named PCB-2.

[0025] Characterization results of the product obtained in Example 2:

[0026] Figure 2 Figure for the change of the powdery boron cluster supramolecular photoinduced reversible color-changing material PCB-2 obtained in Example 2 before and after ultraviolet light irradiation. The results show that the prepared material is an off-white powdery solid, which turns green after ultraviolet light irradiation, and the color gradually returns to the original color after removing the ultraviolet light. The results also show that within a certain range, changing the molar ratio of CB[7] to 2,4,6-tris(4-pyridyl)-1,3,5-triazine and then combining it with the boron cluster to construct a supramolecular material still has photoinduced reversible color-changing performance.

Claims

1. A synthesis method of a three-component supramolecular photoinduced reversible color-changing material composed of a boron cluster, cucurbituril, and a triazine unit, comprising the following steps: A. Encapsulate 2,4,6-tris(4-pyridyl)-1,3,5-triazine into the cavity of cucurbituril: Dissolve 2,4,6-tris(4-pyridyl)-1,3,5-triazine in a hydrochloric acid solution, then add cucurbituril dissolved in the hydrochloric acid solution, and stir at 120 °C under reflux for 12 hours to obtain a cucurbituril solution encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine; B. Combine the boron cluster and the cucurbituril encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine through supramolecular self-assembly to construct a three-component supramolecular material: Add an aqueous solution of the boron cluster to the cucurbituril solution encapsulating 2,4,6-tris(4-pyridyl)-1,3,5-triazine obtained in step A, continuously stir to allow the boron cluster and cucurbituril to fully combine, filter and separate the solid, and dry it to obtain a supramolecular material composed of three components: 2,4,6-tris(4-pyridyl)-1,3,5-triazine, cucurbituril, and the boron cluster.

2. The preparation scheme according to claim 1, characterized in that, The constructed supramolecular material simultaneously includes three components: a boron cluster, cucurbituril, and 2,4,6-tris(4-pyridyl)-1,3,5-triazine.

3. The preparation method according to claim 1, wherein The boron cluster is the dodecahydrododecaborate anion.

4. The preparation scheme according to claim 1, characterized in that, The cucurbituril is cucurbituril[7] (CB[7]).

5. According to the preparation scheme described in claim 1, it is characterized in that, The constructed supramolecular material has a photoinduced reversible color-changing behavior.

6. According to the preparation scheme described in claim 1, it is characterized in that, The constructed supramolecular material can change from off-white to green.

7. According to the preparation scheme described in claims 1-6, a supramolecular photoinduced reversible color-changing material composed of three components: 2,4,6-tris(4-pyridyl)-1,3,5-triazine, cucurbituril, and the boron cluster is constructed.

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