Qilu University of Technology Ji Wenhua‘s research group has made progress in the preparation and application of COFs

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1. Research on selective catalysis of porous organic polymer carrying metals
Recently, Ji Wenhua‘s research group at Qilu University of Technology has made important progress in the study of porous organic polymers carrying metal selective catalysis. Related work was published in Organic Letters under the title of "Covalent Organic Framework as a Heterogeneous Ligand for the Regioselective Oxidative Heck Reaction".

Covalent Organic Framework (COF) shows unique advantages in the field of catalysis due to its abundant active sites, regular and adjustable pore structure, high stability and good reusability, and is widely used in organic The chemical and stereoselective catalysis of the reaction. However, its research on regioselective catalysis has not been reported yet.

The Heck reaction is one of the important reactions for the construction of C-C bonds. Its products are linear and branched, which generally depend on the electron bias of the olefin substrate. For electrically non-biased olefins, only a mixture of linear and branched chains can be obtained, so the regulation of linear and branched products through ligands has important theoretical and application value.

The research group used the N and O in COF as coordination sites to coordinate it with palladium. It showed extremely superior regioselectivity and wide substrate applicability in the Heck oxidation reaction. The ratio of linear to branched products can be Up to> 100:1. Relevant experiments have proved that the regular pore structure and coordination mode of COF play an important role in regional selective regulation.

 This research result not only shows that COF has the effect of regulating regioselectivity, but also provides ideas for the design and synthesis of new COFs to regulate various regioselective organic reactions. The research work was mainly completed by Han Jiyao, a 2018 master student, and was assisted by other researchers in the research group. Dr. Wang Qiong from Shandong Normal University conducted relevant theoretical calculations and explained the rationality of the linear products from the perspective of the coordination of COF and palladium.

Paper link:

https://dx.doi.org/10.1021/acs.orglett.0c00061

2. Research on the preparation and application of covalent organic frameworks (COFs)
Recently, Qi Wenhua’s research group at Qilu University of Technology has made important progress in the preparation and application of covalent organic frameworks (COFs). The relevant results are "Facile synthesis of trifluoromethyl covalent organic framework for the efficient microextraction of per-and polyfluorinated alkyl substances from "Milk products" was published in Journal of Chromatography A.

COFs have the advantages of adjustable functions, controllable pore structure, large specific surface area, high thermal and chemical stability, etc., and have a wide range of applications in the fields of gas adsorption, drug delivery, proton conduction, and heterogeneous catalysis. The diversity of COFs structure and abundant functional groups also make them of important application value in separation sciences such as chromatographic analysis and sample pretreatment. Perfluorinated and polyfluoroalkyl substances (PFASs) have attracted attention because of their continuous release and ubiquity in the environment. Since diet is considered the main route of exposure to PFASs, it is recommended to monitor PFASs in foods (such as milk, honey, fish) for risk assessment in Canada and European countries. As animal-derived food, milk and its derivatives are consumed in large quantities by humans. Compared with the environmental matrix, the matrix of dairy products is more complex and has a stronger matrix effect. Therefore, it is very necessary to achieve efficient and sensitive sample pretreatment of PFASs in dairy products.

The synthesized CF3-COF material is used as a solid phase microextraction (SPME) coating. The SPME coating has an ordered pore structure, fluorophilicity and hydrophobicity, which can effectively inhibit the matrix effect and has a good extraction of PFASs performance. In this paper, the CF3-COF-SPME tandem mass spectrometry method was used to successfully analyze 8 PFASs in dairy products. This method has the characteristics of wide linear range, low detection limit and good repeatability.

The main points of the paper: 1. A simple method was used to synthesize a trifluoromethyl covalent organic framework (CF3-COF) at room temperature; 2. The characteristic of CF3-COF is extraordinary for single and polyfluoroalkyl substances (PFASs) Affinity; 3. Density functional theory is used to prove the affinity of fluorine; 4. CF3-COF can be used for solid-phase microextraction of PFASs in dairy products.

This research provides new ideas for the preparation and application of functional COFs. The work was carried out under the guidance of Associate Researcher Ji Wenhua and Professor Wang Xiao, and the experiment was completed by Sun Xiaowei, a 2018 master student of the center. The above research projects have been supported by the National Natural Science Foundation of China. (Source: New material information compiled in Qilu University of Technology)

Paper link:

https://doi.org/10.1016/j.chroma.2020.461197
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