Chemist Corwin Hansch, 92, 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 had suffered from a prolonged bout with pneumonia.

Dr. Hansch was known as the "father of computer-assisted molecule design" for his development of Quantitative Structure Activity Relationships, known colloquially as QSARs, a series of equations that 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 manpower for his laboratory research was undergraduate students - not the graduate students and postdoctoral fellows that most scientists rely on to implement their ideas.

By the time of his retirement, Dr. Hansch had published more than 250 papers in scientific journals, with at least 43 undergraduate coauthors. Each of them had to be trained in how to do the research, but by the time they had learned the procedures they were often ready to leave for graduate school, medical school, or some other endeavor.

Corwin Herman Hansch was born Oct. 6, 1918, in Kenmare, N.D. He received his doctorate from New York University in 1944. Upon graduation he joined the wartime Manhattan Project that was developing the atomic bomb.

- Los Angeles Times