新加坡国立大学Kian Ping Loh研究团队在共价有机框架中的主干中注入假轮烷来划分其内层间空间。相关论文发表在2020年11月2日的《自然-化学》。
Title: Partitioning the interlayer space of covalent organic frameworks by embedding pseudorotaxanes in their backbones
Author: Xing Li, Hai-Sen Xu, Kai Leng, See Wee Chee, Xiaoxu Zhao, Noopur Jain, Hai Xu, Jingsi Qiao, Qiang Gao, In-Hyeok Park, Su Ying Quek, Utkur Mirsaidov, Kian Ping Loh
Abstract: Mono- or few-layer sheets of covalent organic frameworks (COFs) represent an attractive platform of two-dimensional materials that hold promise for tailor-made functionality and pores, through judicious design of the COF building blocks. But although a wide variety of layered COFs have been synthesized, cleaving their interlayer stacking to obtain COF sheets of uniform thickness has remained challenging. Here, we have partitioned the interlayer space in COFs by incorporating pseudorotaxane units into their backbones. Macrocyclic hosts based on crown ethers were embedded into either a ditopic or a tetratopic acylhydrazide building block. Reaction with a tritopic aldehyde linker led to the formation of acylhydrazone-based layered COFs in which one basal plane is composed of either one layer, in the case of the ditopic macrocyclic component, or two adjacent layers covalently held together by its tetratopic counterpart. When a viologen threading unit is introduced, the formation of a host–guest complex facilitates the self-exfoliation of the COFs into crystalline monolayers or bilayers, respectively.