Getting a handle on molecular ‘baskets’

Denison University Granville, Ohio, United States 

Tell someone you’re learning how to build baskets in college, and most folks would think of that mythological class Basketweaving 101 — a catch phrase for an easy “A.”

No such thing here. In Jordan Fantini’s chemistry research lab, students are learning how to make calixarenes, basket-shaped molecules that detect important compounds through their complementary shape and electronic charge, like a baseball glove is designed to recognize a baseball instead of a basketball.

Fantini, an associate professor of chemistry and biochemistry, has discovered and refined a process that expands the potential of calixarenes. Here’s how he and his students build a better basket.

Calixarenes are organic molecules that have rings of atoms linked together to form a larger ring. This large ring takes a shape like a basket with three predominant features; an upper “rim” that generally holds a specific electronic charge; a lower rim that stablizes the molecular shape; and in between, a so-called methylene bridge that connects them. Calixarenes are very useful in detecting dissolved substances because they can be created in a variety of shapes and charges made to “fit” those substances, like putting three-dimensional puzzle pieces together.

But, while calixarenes are useful in detecting compounds, they’re not always so good atremoving them. Selective removal of substances is desirable in many applications, such as hazardous nuclear waste or water pollutants.

Fantini discovered a way to attach a “handle” to a calixarene by making a molecular substitution at one of its methylene bridges, without altering its shape and charge. This results in a way to link the calixarene to a small solid bead, made of plastic or silicon, for example. These beads, coated with designed calixarenes, can then be used to trap molecules in a liquid. When the beads are filtered out of the liquid, the selected molecules come along. The beads can be reused, a strong attribute for any purification process, as it enhances sustainability and provides a more cost-effective model.


So, each time they step into their lab in the newly renovated and expanded Ebaugh Laboratories, Fantini and his students expand the potential of these organic molecules and add to the base of both pure and practical chemistry scientific knowledge.

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