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Chemistry In Pictures

Chemistry in Pictures: Polymorphs and perseverance

by Brianna Barbu
April 6, 2023


A microscope image of red crystals. Some of the crystals are short and blocky, others are long and cylindrical.
Credit: Shaista Hassan Lone

This image by Shaista Hassan Lone, a scientist at the University of Kashmir, shows two polymorphs—different crystal structures—of 4-(dimethylamino)benzaldehyde. When Lone initially set out to grow crystals of the compound to study their ability to change color in response to mechanical force, she expected that all the crystals would take the same blocky shape. For the most part, they did. But there were also some cylindrical crystals growing alongside the blocky ones. Her mentor asked her to try to grow samples of both crystal forms for single-crystal diffraction to confirm that they were polymorphs of the same compound. The blocky crystals were relatively easy, but it took her over 25 tries to grow diffraction-worthy cylindrical crystals—she even started dreaming about polymorphs, she says. Eventually, she realized that the crystal growth was temperature-dependent and figured out conditions to coax the compound into producing quality cylinders.

Submitted by Shaista Hassan Lone

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