Crystals in a spin
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Contrary to conventional wisdom, stirring a chemical solution can promote the rapid growth of large, high-quality crystals. The key is to spike the stirred solution with polymers that promote crystallization.
High-quality crystals are essential for X-ray crystallography, a gold-standard technique for determining the structures of novel chemical compounds. Many industrial chemical operations also use crystallization. The process typically involves dissolving the compound of interest in a solvent, and then leaving it undisturbed for hours to days for crystals of the compound to form.
Now, a team led by researchers from the Institute for Basic Science in South Korea has shown that adding poly(ionic liquid) polymers to the solution and stirring can reduce this time to just minutes.
The shear forces induced by stirring cause the polymers to disentangle, exposing more of the polymer surface, which attracts a coating of solvent molecules. As fewer solvent molecules remain to solvate the compound to be crystallized, large crystals begin to form quickly.
- Nature 579, 73–79 (2020). doi: 10.1038/s41586-020-2042-1