阅读说明：本技术 一种三维荧光共价有机框架材料及其制备方法与应用 (Three-dimensional fluorescent covalent organic framework material and preparation method and application thereof ) 是由 顾志国 刘勇 晏晓东 张文达 路惠舒 石亚翔 李涛 符秋婷 于 2020-06-08 设计创作，主要内容包括：本发明公开了一种三维荧光共价有机框架材料及其制备方法与应用,是以六甲基联苯醛类衍生物与一系列芘基胺类衍生物为原料,邻二氯苯与均三甲苯为溶剂,乙酸为催化剂,溶剂热反应若干天。反应结束后,依次用DMF,THF抽滤洗涤,索氏提取24小时后真空干燥得黄色粉末,即为目标产物。以基于位阻效应的六甲基联苯四醛和具有荧光性质的芘基四胺作为构筑单体,合成出的“Turn-on”型三维荧光共价有机框架具有丰富的空腔结构以及共轭的三维骨架,不但避免了荧光基团的聚集诱导淬灭效应,而且提高了材料主客体响应的灵敏度,使材料在荧光传感领域展现出良好的应用前景,并首次将三维共价有机框架应用于VOCs分子解码领域。(The invention discloses a three-dimensional fluorescent covalent organic framework material and a preparation method and application thereof. After the reaction is finished, sequentially performing suction filtration and washing by using DMF and THF, performing Soxhlet extraction for 24 hours, and then performing vacuum drying to obtain yellow powder, namely the target product. The 'Turn-on' type three-dimensional fluorescent covalent organic framework synthesized by taking hexamethyl biphenyl tetra-aldehyde based on steric hindrance effect and pyrenyl tetra-amine with fluorescence as building monomers has rich cavity structures and conjugated three-dimensional frameworks, thereby not only avoiding aggregation induced quenching effect of fluorescent groups, but also improving the sensitivity of host-guest response of the material, leading the material to show good application prospect in the field of fluorescence sensing, and applying the three-dimensional covalent organic framework to the field of VOCs molecular decoding for the first time.)

1. A three-dimensional fluorescent covalent organic framework material is characterized by being represented by the following structural formula:

2. a preparation method of a three-dimensional fluorescent covalent organic framework material is characterized by comprising the following steps: the method comprises the steps of dissolving hexamethyl biphenyl aldehyde derivatives and pyrenyl amine derivatives serving as raw materials in a reaction solvent, and reacting under the action of a catalyst to obtain the three-dimensional fluorescent covalent organic framework material.

3. The method of claim 2, wherein the hexamethyl biphenyl aldehyde derivative has the following formula:

wherein, R is independent of each other and respectively represents C1-C5 alkyl or C1-C6 alkoxy.

4. The method for preparing the three-dimensional fluorescent covalent organic framework material according to claim 2, wherein the pyrenyl amine derivative has a molecular formula as follows:

5. the method for preparing the three-dimensional fluorescent covalent organic framework material according to claim 2, wherein the mass ratio of the hexamethyl biphenyl aldehyde derivatives to the pyrenyl amine derivatives is 1: 3-3: 1.

6. The method for preparing the three-dimensional fluorescent covalent organic framework material according to claim 2, wherein the reaction solvent comprises o-dichlorobenzene and mesitylene, and the volume ratio of the o-dichlorobenzene to the mesitylene is 1: 1-5: 1.

7. The preparation method of the three-dimensional fluorescent covalent organic framework material according to claim 2, wherein the catalyst is 10-20% of the volume of the reaction solvent; the catalyst comprises acetic acid, and the concentration of the acetic acid is 3-6 mol/L.

8. The method for preparing the three-dimensional fluorescent covalent organic framework material according to claim 2, wherein the reaction is performed in a reaction kettle at 110-150 ℃ for 5-7 days.

9. The method for preparing the three-dimensional fluorescent covalent organic framework material according to claim 2, wherein the reaction is finished, then the reaction product is cooled to room temperature, filtered to collect solid, and repeatedly washed, purified and dried; performing the washing with an organic solvent, wherein the organic solvent comprises one or two of N, N-dimethylformamide DMF and tetrahydrofuran THF; the drying condition is vacuum and is 70-100 ℃; the purification mode comprises Soxhlet extraction.

10. The use of the three-dimensional fluorescent covalent organic framework material of claim 1 in fluorescence sensing for molecular decoding of VOCs.

Technical Field

The invention belongs to the field of covalent organic framework materials, and particularly relates to a three-dimensional fluorescent covalent organic framework material and a preparation method and application thereof.

Technical Field

Volatile Organic Compounds (VOCs) are one of the leading causes of air pollution today and have attracted widespread attention worldwide. According to the data of the international agency for research on cancer (IARC), when the content of most of VOCs in the environment exceeds a certain value, biological symptoms such as headache, nausea and chest distress can be caused in a short time; long-term inhalation can seriously damage vision, hearing and the like, endanger internal organs and nervous systems of human bodies, and seriously cause cancer and death. Therefore, monitoring and control of molecules of VOCs is of crucial importance for biotechnology, environmental monitoring and gas separation. However, most of the VOCs sensors reported so far can only selectively capture specific molecules and then selectively convert the recognition events into detectable signals, which means that such VOCs sensors can only satisfy the "one-to-one" recognition of single molecules. Therefore, it is important to design and synthesize a multi-molecular decoder for identifying different kinds of VOCs.

In recent years, fluorescent metal organic frameworks (LMOF) have attracted much attention in the detection of VOCs due to their abundant three-dimensional pore structures and sensitive host-guest responsivity. The three-dimensional pore structure of the LMOF can accommodate the entrance of guest molecules (such as VOCs molecules), and the sensitive host-guest effect can generate special detectable fluorescence signals according to different guest molecules, thereby realizing the one-to-many VOCs molecule decoding. However, due to the instability, especially the chemical instability, of the MOFs, the conditions for using the MOFs as molecular decoders of VOCs are greatly limited, and the current reports LMOF are almost focused on the identification of benzene-based VOCs.

Covalent organic framework materials (COFs) are a new class of crystalline organic porous materials formed by dynamic covalent bonding. Compared with traditional porous carbon materials or MOFs materials, the material has the advantages of low density and high stability, and has attracted more and more attention in fluorescent chemical sensors. At present, related two-dimensional COF materials are used for VOCs molecular decoding, but the two-dimensional COFs materials are formed by stacking through strong pi-pi interaction, and the stacking of most of fluorescent groups can cause fluorescence aggregation induced quenching (ACQ), so that the sensitivity and the recognizable range of the COFs materials as molecular decoders are reduced. The 3DCOFs material has a three-dimensional pore structure similar to that of MOFs materials, and can effectively avoid a fluorescence quenching phenomenon caused by ACQ in the 2DCOFs material. The channel structure of 3D COFs can accommodate the entry of guest molecules, and then change the fluorescence emission wavelength and intensity by energy transfer between the guest molecules and fluorophores, or lower or raise the excited state energy by Charge Transfer (CT). Through the signal difference displayed after the host-object contact, the identification of aromatic or other types of VOCs molecules can be realized.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a three-dimensional fluorescent covalent organic framework material and a preparation method and application thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a three-dimensional fluorescent covalent organic framework material is shown in the following structural formula:

a preparation method of a three-dimensional fluorescent covalent organic framework material is characterized in that a tetrahedral construction unit hexamethyl biphenyl aldehyde derivative based on steric hindrance effect and a pyrenyl amine derivative are used as raw materials and dissolved in a reaction solvent, and the three-dimensional fluorescent covalent organic framework material is obtained by reaction under the action of a catalyst, wherein the molecular formula of the hexamethyl biphenyl aldehyde derivative is as follows:

wherein, R is independent of each other and respectively represents C1-C5 alkyl or C1-C6 alkoxy.

The molecular formula of the pyrenyl amine derivative is as follows:

preferably, the mass ratio of the hexamethyl biphenyl aldehyde derivative to the pyrenyl amine derivative is 1: 3-3: 1.

Preferably, the reaction solvent comprises o-dichlorobenzene and mesitylene, and the volume ratio of the o-dichlorobenzene to the mesitylene is 1: 1-5: 1.

Preferably, the catalyst is 10-20% of the volume of the reaction solvent.

Preferably, the catalyst comprises acetic acid, and the concentration of the acetic acid is 3-6 mol/L.

The reaction is kept still for 5-7 days at 110-150 ℃ in a reaction kettle. And after the reaction is finished, cooling to room temperature, filtering and collecting a solid, and repeatedly washing, purifying and drying.

Performing the washing with an organic solvent, wherein the organic solvent comprises one or more of N, N-dimethylformamide DMF and tetrahydrofuran THF; the drying condition is vacuum and is 70-100 ℃; the purification mode comprises Soxhlet extraction.

The invention also aims to provide a three-dimensional fluorescent covalent organic framework material which is prepared by the method and can be used in the field of fluorescence sensing for decoding VOCs molecules.

Has the advantages that:

the invention skillfully uses a tetrahedral building block with steric effect to build a conjugated three-dimensional fluorescent covalent organic framework material. By the method, the three-dimensional fluorescent covalent organic framework based on the hexamethylbiphenyl framework can be prepared, the framework has a stable framework structure, a proper pore channel structure allows the free access of guest molecules, pyrenyl units uniformly dispersed in the three-dimensional framework can effectively avoid aggregation induced fluorescence quenching effect, and the semi-conjugated framework structure can improve the host-guest response sensitivity of the material, so that the test range and sensitivity of the material as a fluorescent sensor are improved.

Drawings

FIG. 1 example 1 a synthetic scheme for the preparation of a three-dimensional fluorescent covalent organic framework material;

FIG. 2 is an electron micrograph of a three-dimensional fluorescent covalent organic framework material prepared in example 1;

FIG. 3 is a transmission electron micrograph of the three-dimensional fluorescent covalent organic framework material prepared in example 1;

FIG. 4 is a powder X-ray diffraction pattern of the three-dimensional fluorescent covalent organic framework material prepared in example 1;

FIG. 5 is a nitrogen adsorption/desorption isotherm plot of the three-dimensional fluorescent covalent organic framework material prepared in example 1;

FIG. 6 is a fluorescent sensing (VOCs molecular decoding) diagram of the three-dimensional fluorescent covalent organic framework material prepared in example 1.

Detailed Description

The technical solution of the present invention will be further described in detail with reference to the following specific examples.