This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Many of the common materials we encounter in our daily lives are crystalline, including ice, salt and sugar. The crystal structures of some solids are formed from molecules arranged in simple geometric patterns, and these patterns can be changed to give the solids special properties required for high-tech applications.
However, changing these connections requires extreme measures, such as high heat, leaving researchers with the challenge of finding an easier transformation method. Newer so-called "soft crystals" can be modified more easily. Now, researchers from the Institute of Industrial Science at The University of Tokyo and the Graduate School of Science at the University of Hyogo have used sophisticated instruments to learn more about these unusual materials.
The findings are published in Small. Modifying a solid through a phase transition is complicated and difficult to observe. Despite these difficulties, researchers have continually attempted to learn more about phase transitions and improve research techniques.
This is particularly relevant because certain substances have specialized applications in electronics and other technologies based on unique molecular connections. In the study, the researchers examined extremely small crystals of a rhenium complex molecule. The crystals, which varied in size, were measured with micrometer resolution.
A micrometer is one-millionth of a meter, and the crystals were thinner than a single hair. These compounds were exposed to vapors of the liquid solvent chloroform and observed using an extremely powerful laser microscope and X-ray diffraction, a technique that shows molecular patterns. "We were able to see drastic changes in these crystals as they absorbed the chloroform," says lead author Xiao Ma.
"As chloroform migrated into the samples, areas made of more than 10,000 molecules moved cooperatively. This movement produced a phase transition changing the structure of the crystal." Examination of crystals as small as one micrometer showed other interesting behaviors as the chloroform soaked into the sample. "Some samples showed deliquescence," explains senior author Kazuyuki Ishii, "meaning that the crystal absorbed so much chloroform that parts of it dissolved." Another novel observation showed that some crystals moved as they absorbed chloroform because of changes in volume and recrystallization.
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