Linker Exchange as Facile Method for Post-Synthetic Modification of β-Ketoenamine-linked Covalent Organic Frameworks

Abstract

Post-synthetic linker exchange performed on covalent organic frameworks (COFs) has become an important method to introduce functional building blocks into their backbone and thus to tune their chemical and physical properties. However, the linker exchange method has so far only been described for COFs with relatively weak linkages like imines. Herein, it is shown that this method can be also used for a post-synthetic linker exchange reaction on a β-ketoenamine linked COF. The time needed to achieve considerable linker exchange is much prolonged compared to other COFs with less stable linkages, however, this enables to achieve very good control on the ratio of the respective building blocks within the framework.

Keywords: building block exchanges; covalent organic frameworks; linker exchanges; post-synthetic modifications; β-ketoenamine linkages.