Synthesis Synergy

FAYETTEVILLE, Ark. — From combating cancer and AIDS to developing better body armor, scientists use chemistry to synthesize new materials — a painstaking process that can take years to develop. Organic chemist David Vicic takes a novel approach to synthesizing molecules of medical and industrial importance — instead of screening catalysts for the best yield of product, he examines the fate of the metals that help catalyze the reactions in hopes of learning about the mechanisms that drive the reaction, and his work has gained the attention of the U. S. Department of Energy.

Vicic has received $390,000 from the Department of Energy to study ways to synthesize organic materials efficiently and in ways that are environmentally sound. This could lead to better methods for synthesizing drugs and industrial materials.

“I think there’s only so much you can learn from looking at the yields” of the end product, said Vicic, assistant professor of chemistry and biochemistry in the J. William Fulbright College of Arts and Sciences. The synthesis of complex drugs requires many intermediate steps, and it is these steps that hold the key to improving efficiency.

Studying the properties of transitional metal-based catalysts used in synthetic reactions require specialized techniques because often these metals are transient and appear and disappear in a matter of seconds. Vicic and his group decided to tackle this issue by drawing up an idealized reaction and then seeking the best ways to prepare and study the intermediate products one step at a time.

Vicic and his colleagues are also pushing for the use of the inexpensive metal nickel in such reactions. Nickel has not been used as much as other expensive metals like palladium in catalytic organic synthesis because a major commercial source of nickel reacts with air to form catalytically inactive materials.

The Vicic lab has developed new catalyst precursors that are air-stable, and can be stored on a standard laboratory bench top.  The active forms of the catalysts are then generated during the course of the synthetic reaction.  These active forms may be air-sensitive, however, so Vicic’s group also is using computational chemistry to study the geometries and electron structures of the active forms of the molecules to help predict how they will react. Knowing the mechanisms that take place in the middle of the reaction can lead to the refinement of the interactions, which could lead to broad synthetic applications.

 “If you know the mechanisms, you can make modifications to do more sophisticated things,” Vicic said.

The synthetic methods that Vicic and his group are developing are environmentally benign.  They only use a catalytic amount of nickel, which can be recycled, and produce a zinc byproduct that is non-toxic.

“All of our reactions also proceed at room temperature, so they’re very mild and don’t require additional energy,” Vicic said.