A microscope image showing a porous, crystalline material called a metal-organic framework, or MOF (the material in purple). This MOF is made from cobalt(II) sulfate heptahydrate, 5-aminoisophthalic acid and 4,4′-bipyridine, and it is shown in its hydrated state. Credit: Travis Mitchell How does water leave a sponge?
In a new study, scientists answer this question in detail for a porous, crystalline material made from metal and organic building blocks— specifically, cobalt(II) sulfate heptahydrate, 5-aminoisophthalic acid and 4,4′-bipyridine.
Using advanced techniques, researchers studied how this crystalline sponge changed shape as it went from a hydrated state to a dehydrated state. The observations were elaborate, allowing the team to “see” when and how three individual water molecules left the material as it dried out.
Crystalline sponges of this kind belong to a class of materials called metal-organic frameworks (MOFs), which hold potential for applications such as trapping pollutants or storing fuel at low pressures.
“This was a really nice, detailed example of using dynamic in-situ X-ray diffraction to study the transformation of a MOF crystal,” says Jason Benedict, Ph.D., associate professor of chemistry in the University at Buffalo College of Arts and Sciences. “We initiate a reaction—a dehydration. Then we monitor it with X-rays, solving […]
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