Harden M. McConnell

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Harden M. McConnell (born July 18, 1927 in Richmond, Virginia) is an American physical chemist at Stanford University.[1]

Birth and education[edit]

Harden M. McConnell was born on July 18, 1927 in Richmond, Virginia. He completed his Bachelor of Science from George Washington University in 1947 and his PhD from the California Institute of Technology in 1951. He is a Robert Eckles Swain Emeritus Professor at Stanford University.


He did important research to the understanding of the relation between molecular electronic structure and electron and nuclear magnetic resonance spectra during the period of 1955 through 1965. After that, he developed the technique of spin-labels, whereby electron and nuclear magnetic resonance spectra can be used to study the structure and kinetics of proteins and membranes.

He 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 (see McConnell equation for details). His theoretical and experimental investigations of the anisotropic nuclear hyperfine interactions 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. He also 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. These motions include the rates of translational diffusion of lipids in bilayer membranes as well as the rates of trans membrane phospholipid "flip-flop". In fact nitroxide free radical "spin labels" provided some of the earliest evidence for the fluidity of biological membranes.

His recent research is concerned with the physical chemistry of biological membranes. These studies range all the way from lipid monolayers at the air-water interface to the regions of membrane-membrane contact that are important in immunology. An important contribution was the introduction of supported lipid bilayers to mimic cell surfaces. For example this system was used to mimic antigen presentation whereby a specific molecule of the majorhistocompatibility complex is incorporated into the bilayer, a specific antigenic peptide is added, and the combined system used to stimulate a specific T - helper cell.

In 1983 McConnell founded Molecular Devices Corporation along with three former graduate students and post docs (Gillian Humphries, j. Wallace Parce and Dean Hafeman) together witl a talented engineer Calvin Chow. The company produced instrumentation for biochemical analysis and drug discovery. The company had over 1,000 employees when it was acquired in 2007. McConnell served on the Board of Directors between 1983 and 2007.

Awards and honours[edit]

He was awarded the Wolf Prize in Chemistry in 1983/84 for "his studies of the electronic structure of molecules through paramagnetic resonance spectroscopy and for the introduction and biological applications of spin label techniques".[2]

He has also received several awards and honours. Following are the awards and honours received by Dr. McConnell.


External links[edit]