Scientists have woven the first 3-D covalent organic frameworks (COFs) from helical organic threads.

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Scientists have woven the first 3-D covalent organic frameworks (COFs) from helical organic threads.

Post by Cr6 on Tue Feb 02, 2016 2:10 am

Date: January 21, 2016
Source: DOE/Lawrence Berkeley National Laboratory
Summary: Scientists have woven the first 3-D covalent organic frameworks (COFs) from helical organic threads. The woven COFs display significant advantages in structural flexibility, resiliency and reversibility over previous COFs.

(More at link: http://www.sciencedaily.com/releases/2016/01/160121185624.htm)

COF-505 is the first 3-D covalent organic framework to be made by weaving together helical organic threads, a fabrication technique that yields significant advantages in structural flexibility, resiliency and reversibility over previous COFs.
Credit: courtesy of Omar Yaghi, Berkeley Lab and UC Berkeley

There are many different ways to make nanomaterials but weaving, the oldest and most enduring method of making fabrics, has not been one of them -- until now. An international collaboration led by scientists at the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley, has woven the first three-dimensional covalent organic frameworks (COFs) from helical organic threads. The woven COFs display significant advantages in structural flexibility, resiliency and reversibility over previous COFs -- materials that are highly prized for their potential to capture and store carbon dioxide then convert it into valuable chemical products.

"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," says Omar Yaghi, a chemist who holds joint appointments with Berkeley Lab's Materials Sciences Division and UC Berkeley's Chemistry Department, and is the co-director of the Kavli Energy NanoScience Institute (Kavli-ENSI).

"Weaving in chemistry has been long sought after and is unknown in biology," Yaghi says. "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."

Yaghi is the corresponding author of a paper in Science reporting this new technique. The paper is titled "Weaving of organic threads into a crystalline covalent organic framework." The lead authors are Yuzhong Liu, Yanhang Ma and Yingbo Zhao. Other co-authors are Xixi Sun, Felipe Gándara, Hiroyasu Furukawa, Zheng Liu, Hanyu Zhu, Chenhui Zhu, Kazutomo Suenaga, Peter Oleynikov, Ahmad Alshammari, Xiang Zhang and Osamu Terasaki.

COFs and their cousin materials, metal organic frameworks (MOFs), are porous three-dimensional crystals with extraordinarily large internal surface areas that can absorb and store enormous quantities of targeted molecules. Invented by Yaghi, COFs and MOFs consist of molecules (organics for COFs and metal-organics for MOFs) that are stitched into large and extended netlike frameworks whose structures are held together by strong chemical bonds. Such frameworks show great promise for, among other applications, carbon sequestration.

Through another technique developed by Yaghi, called "reticular chemistry," these frameworks can also be embedded with catalysts to carry out desired functions: for example, reducing carbon dioxide into carbon monoxide, which serves as a primary building block for a wide range of chemical products including fuels, pharmaceuticals and plastics.


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