
Harden M. McConnell
Wolf Prize Laureate in Chemistry 1983/4

The Chemistry Prize Committee for 1983/4 has unanimously chosen the following three candidates to equally share the award: Herbert S, Gutowsky ,Harden M. McConnell and John S. Waugh.
Harden M. McConnell
Stanford University California
Stanford, California, USA
“for his studies of the electronic structure of molecules through paramagnetic resonance spectroscopy and for the introduction and biological applications of spin label techniques.”
Magnetic resonance spectroscopy has made a singular contribution to chemistry in theory, structure and dynamics of molecules in liquids and solids. This is reflected in the choice of the recipients of the Wolf Prize in Chemistry for 1983/84.
Professor Harden M. McConnell recognized that the discovery of nuclear hyperfine interactions in aromatic free radicals represented a major breakthrough in the study of the electronic structure of unsaturated hydrocarbons. His theoretical and experimental studies of nuclear hyperfine interactions in such compounds showed conclusively that this interaction gave a measure of the unpaired electron spin densities on the carbon atoms. McConnell’s theoretical and experimental investigations of the anisotropic nuclear hyperfine interaction laid a firm foundation for the analysis of the paramagnetic resonance spectra of organic free radicals in. molecular crystals. His work also provided the first experimental demonstration of a negative spin density at a proton. Finally, McConnell realized that certain nitroxide free radicals had the potential of providing labels for studying molecular motions. His introduction of ‘spin labels’ has led to a deep understanding of such motions, and to extensive applications in many biological systems of great interest.
