Molecular weaving of chicken-wire covalent organic frameworks

Molecular weaving is the interlacing of covalently linked threads to make extended structures. Although weaving based on 3D networks has been reported, the 2D forms remain largely unexplored. Reticular chemistry uses mutually embracing tetrahedral metal complexes as crossing points, which, when linked, typically lead to 3D woven structures. Realizing 2D weaving patterns requires crossing points with an overall planar geometry. We show that polynuclear helicates composed of multiple metal-complex units, and therefore multiple turns, are well suited in this regard. By reticulating helicate units, we successfully obtained 2D weaving structures based on the familiar chicken-wire pattern. [Display omitted] •Design and synthesis of molecular chicken wire via COF chemistry•The number of turns and the crossing points direct how the threads are woven in the COFs•A new approach for achieving 2D woven COFs by installing functionalized polynuclear helicates Helical building units were used in the synthesis of molecular chicken wires. The creation of such 2D patterns, the most prevalent macroscopic type of weaving in society, has been uncommon. In this work, we demonstrate that helically assembled molecules, helicates, composed of multiple mutually embracing complexes, can indeed be used for accessing the planar building units necessary for making 2D woven patterns. By controlling the number of turns in these helical building units, we can generate two distinct patterns that resemble chicken-wire fences. We believe that such arrangements are of fundamental importance for venturing further into achieving properties that make woven fabric and metal fences so ubiquitous in our society. Preparing woven 2D structures of COFs is challenging. In this study, Yaghi and co-workers use helicates composed of multiple mutually embracing complexes to access the planar building units necessary for making 2D patterns. They achieve two distinct chicken-wire patterns by controlling the number of turns in these helical building units.