C. Hansch, study helped develop new drugs

Chemist Corwin Hansch, who pioneered the field of relating a molecule's chemical structure to its biological activity, an approach widely used in developing new drugs and other commercial chemicals, died in Claremont, Calif., on May 8.

He was 92 and had suffered from a prolonged bout with pneumonia.

Hansch was known as the "father of computer-assisted molecule design" for his development of Quantitative Structure Activity Relationships, known colloquially as QSARs, which allow chemists to modify drugs and other molecules in a predictable manner to achieve desired characteristics.

He did it, moreover, at Pomona College, a liberal arts institution where his primary source of research help for his laboratory work was undergraduate students -- not the graduate students and postdoctoral fellows that most scientists rely on to implement their ideas.

QSARs, known as Hansch equations, are a series of equations that relate observable biological effects to specific, measurable properties of molecules.

A promising drug, for example, might prove to have low toxicity in general, but one disturbing side effect. The Hansch equation suggests how the molecule should be modified to minimize the adverse properties.