John D. Roberts
California Institute of Technology
Election Year: 1956
Primary Section: 14, Chemistry
Secondary Section: 21, Biochemistry
Membership Type: Member
Physical organic chemistry, especially conformational analysis because most molecules of interest in organic and biochemistry are relatively "loose-jointed" and can exist in two or more different spatial arrangements (conformations) that are important to both their chemical and biological properties. In our research, we try to evaluate steric (bulk), electrostatic (charges and dipoles), and hydrogen-bonding effects of substituent groups, as well solvent effects on them, in influencing the positions of conformational equilibria of simple substances that are of such nature either to be important themselves or reasonably presumed to have relevance to the understanding of conformational preferences of biochemically significant compounds. These studies are most easily carried out with the aid of nuclear magnetic resonance spectroscopy and this, using the resonances of 1H, 13C, 15N, or 31P as needed, is the instrumentation of choice, implemented when possible by the use of liquid-crystal or lyotropic solvent media. Such research may not seem very sophisticated relative to the present state of knowledge of chemistry, but the fact is that not nearly as much is known as might be expected from gas-phase theoretical calculations about the interactions of various kinds of substituent groups in aqueous and non-aqueous solutions. Our results actually provide an important testing ground for quantum calculations for relatively small molecules in different types of solvents.