Chem. J. Chinese Universities ›› 2020, Vol. 41 ›› Issue (8): 1792.doi: 10.7503/cjcu20200185

• Organic Chemistry • Previous Articles     Next Articles

Synthesis and Characterization of Imine-based Covalent Organic Framework(COF-LZU1) in Supercritical Carbon Dioxide

WANG Yang1, WANG Sidi2, TANG Shaokun1,2   

  1. 1. Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering&Technology, Tianjin University, Tianjin 300072, China;
    2. Collaborative Innovation Center of Chemical Science and Engineering(Tianjin), Tianjin University, Tianjin 300072, China
  • Received:2020-04-07 Online:2020-08-10 Published:2020-07-31
  • Supported by:
    Supported by the National Natural Science Foundation of China(No.51971001) and the Open Project Program of Key Laboratory of Metallurgical Emission Reduction & Resources Recycling(Anhui University of Technology), Ministry of Education, China(No.JKF20-6).

Abstract: This study concerned the utilization of supercritical CO2(scCO2) for the synthesis of covalent organic framework(COF). One kind of imine-based covalent organic framework, COF-LZU1, was prepared via the condensation of 1,3,5-triformylbenzene and p-phenylenediamine with acetic acid as catalyst and N,N-dimethylformamide(DMF) as co-solvent in scCO2. The effects of co-solvent type, temperature, pressure, time, acid volume and molar ratio of reactants on the crystal structure and microstructure of COF-LZU1 were investigated. Increasing the reaction temperature could increase the solubility of the reactants in scCO2 and promote the reaction. The extension of the reaction time was conducive to the maturity of crystals and the improvement of crystallinity. Acetic acid not only catalyzed the reaction, but also acted as a morphology guide agent, different morphologies of COF-LZU1(spheres, blocks and nanorods) could be obtained by changing volume of acetic acid. When the content of p-phenylenediamine in the reaction was too high, it would interfered with the orderly combination of aldehyde groups and amino groups in the reaction process, resulting in a reduction in crystallinity and the declining degree of appearance. The particles synthesized with the molar ratio of 1,3,5-triformylbenzene to p-phenylenediamine as 1:1.5 and the volume ratio of HAc to DMF as 1:1 at 60℃, 20 MPa only within 6 h have the advantages of good crystallinity, nanoscale size, and excellent thermal stability up to 550℃. It is the first time that COF materials was successfully synthesized in scCO2. This method offers new route for facile and green synthesis of COFs.

Key words: Imine-based covalent organic framework(COF-LZU1), Supercritical fluid, Reaction crystallization

CLC Number: 

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