Nano-weaving: Synthesis of threaded polymers begins

Weaving is a well-known way of making fabric, but has until now never been used at the molecular level. Scientists have now been able to weave organic threads into a three-dimensional material, using copper as a template. The new material is a COF, covalent organic framework, and is named COF-505. The copper ions can be removed and added without changing the underlying structure, and at the same time the elasticity can be reversibly changed.

"It almost looks like a molecular version of the Vikings chain-armour. The material is very flexible," says Peter Oleynikov, researcher at the Department of Materials and Environmental Chemistry at Stockholm University.

COF's are like MOF's porous three-dimensional crystals with a very large internal surface that can adsorb and store enormous quantities of molecules. A potential application is capture and storage of carbon dioxide, or using COF's as a catalyst to make useful molecules from carbon dioxide.

The research is led by Professor Omar Yaghi at University of California Berkeley. At Stockholm University Professor Osamu Terasaki, PhD Student Yanhang Ma and Researcher Peter Oleynikov have contributed to determine the structure of COF-505 at atomic level from a nano-crystal, using electron crystallography methods.

"It is a difficult, complicated structure and it was very demanding to resolve. We've spent lot of time and efforts on the structure solution. Now we know exactly where the copper is and we can also replace the metal. This opens up many possibilities to make other materials," says Yanhang Ma, PhD Student at the Department of Materials and Environmental Chemistry at Stockholm University.

"Weaving of organic threads into a crystalline covalent organic framework" is published in Science 22 januari 2016.