Scientists have used several different methods to create nanomaterials, but being able to weave has never been accomplished. Now, researchers from the Lawrence Berkeley National Laboratory have woven the first three-dimensional covalent organic frameworks (COFs) from helical organic threads, which possess many advantages in terms of structural flexibility, resiliency and reversibility in comparison to previous COFs.
"We have taken the art of weaving into the atomic and molecular level, giving us a powerful new way of manipulating matter with incredible precision in order to achieve unique and valuable mechanical properties," Omar Yaghi, who participated in the research, said in a press release. "Weaving in chemistry has been long sought after and is unknown in biology. However, we have found a way of weaving organic threads that enables us to design and make complex two- and three-dimensional organic extended structures."
COFs are porous, three-dimensional crystals that possess very large internal surface areas, giving them the ability to store high amounts of targeted molecules. Yaghi, who invented COFs, stitched them into large networks held together by chemical bonds.
In the current study, Yaghi and his team used a copper (I) complex as the foundation for weaving together the organic compound "phenanthroline," which led to the creation of a network of immines that they called COF0505. They subsequently discovered that X-ray and electron diffractions could change the copper ion structure and lead to the restoration of its original state.
"That our system can switch between two states of elasticity reversibly by a simple operation, the first such demonstration in an extended chemical structure, means that cycling between these states can be done repeatedly without degrading or altering the structure," Yaghi said. "Based on these results, it is easy to imagine the creation of molecular cloths that combine unusual resiliency, strength, flexibility and chemical variability in one material."
The findings were published in the Jan. 22 issue of Science.
