Excision of organic macrocycles from covalent organic frameworks.

Molecules are typically synthesized through stepwise processes involving chemical reactions between simple molecular precursors. Here, we report an advance in the synthesis of new organic molecules based on the approach of clip-off chemistry, in which molecules are excised from ordered, extended organic structures. We synthesized macrocycles by selectively cleaving them out of covalent organic frameworks. The synthesized macrocycles include eight macrocyclic polyamides with 114-, 138-, and 162-atom rings, and one 114-atom ring macrocyclic polyimide. This excision approach expands the scope of chemical organic synthesis to previously inaccessible macromolecules. Editor's summary: Typical organic synthesis builds molecules up from small precursors. Taking a different approach, Sánchez-Naya et al. used targeted cleavage of double or triple bonds to synthesize large macrocyclic molecules from even larger covalent organic frameworks. The authors designed the starting material so that the linkers would contain one segment of the target macrocycles. The products included polyamides with 114-, 138-, and 162-atom rings and a polyimide with a 114-atom ring. —Phil Szuromi [ABSTRACT FROM AUTHOR]