COCRYSTALS

Crystals are usually thought of as pure—containing just one type of molecule. In fact, crystallization is often used as a purification method in synthesis laboratories. But sometimes one type of molecule can readily team up with another to form what’s called a cocrystal. Shown here are cocrystals of glucose and table salt, which form with a repeating formula of 2C₆H₁₂O₆·NaCl·H₂O. The largest one in the top photo is about 4 cm long. Chemist Dmitry Shintyakov, who prepares these and other cocrystals for fun, shared his technique. “To make them, prepare a solution by dissolving 100 g of glucose and 15 g of NaCl in 90–100 g of hot water, then let it cool and put it into an open container to allow it to evaporate slowly.” Once a small rhombic crystal forms, Shintyakov attaches it to a thread, submerges it back in the solution, and lets the crystal continue to grow. He grew these crystals in about a month.

Credit: Dmitry Shintyakov

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