Robust immobilization of Au nanoparticles on snowflake structured covalent organic frameworks for highly shape-selective catalysis of cyclization reaction
writer：Mao, CF (Mao, Chunfeng) [1] ; Song, YC (Song, Youchao) [1] ; Zhu, CZ (Zhu, Chenzi) [1] ; Deng, QH (D
keywords：Covalent organic frameworksShape-selective catalysisSpatial confinement effectAu nanoparticlesIsoflavonesCyclization reaction
source：期刊
Issue time：2022年
Isoflavones, which are secondary metabolites, mostly possess potential in antioncogenic, cardiovascular action and antioxidant, etc. However, at present, the direct extraction of isoflavones from plants using enzymatic reaction is not only limited in source, but also low in efficiency. Therefore, it is a challenge to prepare isoflavones efficiently from easily available raw materials by chemical catalysis. In this work, a smart strategy of "amino acid regulated snowflake-structured covalent organic frameworks as alternative catalytic support" is proposed, which can control the pore size and disperse Au nanoparticles (NPs) by strong coordination between Au NPs and amino side chains. Importantly, it is interesting that the catalyst has good synergistic effects with shape-selective catalysis (99% vs 7%), pi-pi interaction of aromatic rings and excellent spatial confinement effect (20 angstrom vs 16 angstrom) during cyclization reaction using Au@COFs-01. In additon, the turnover frequency (TOF) can be enhanced to 530 h(-1). Moreover, Au@COFs-01 can be easily regenerated for five cycles. The reaction mechanism and structure-activity relationship can be proposed by experimental and theoretical calculations. This method of constructing biomimetic COFs with biomass materials provides the basis for the application and design of novel COFs.