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Analytical Chemistry

Joel Henry Hildebrand Award In The Theoretical & Experimental Chemistry Of Liquids

by Jyllian Kemsley
February 10, 2014 | APPEARED IN VOLUME 92, ISSUE 6

Freed
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Credit: CORNELL U PHOTOGRAPHY
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Credit: CORNELL U PHOTOGRAPHY

Sponsored by ExxonMobil Research & Engineering

As a child, Jack H. Freed developed his own “little chemistry laboratory” in his basement, with experiments fueled in part by chemistry books checked out of Brooklyn Public Library.

He then chose to major in chemical engineering as an undergraduate at Yale University. It was a practical choice, he says, driven by uncertainty about the availability of chemistry jobs and an adviser’s recommendation that it was easier to go from chemical engineering to chemistry than the reverse. But the prospect of investigating fundamental science lured him back to chemistry for graduate school at Columbia University, where he worked with electron spin resonance spectroscopy (ESR) pioneer George K. Fraenkel.

At Columbia, “I was involved with both instrumentation development and theory and developed my lifelong professional interest of using methods of ESR to study molecular dynamics in liquids,” Freed says. He joined the faculty at Cornell University in 1963, and he is now the university’s Frank & Robert Laughlin Professor of Physical Chemistry.

Freed was—and is—excited by the ability to know what molecules are doing, through the use of ESR combined with statistical mechanics. ESR is analogous to nuclear magnetic resonance spectroscopy, but it focuses on electron spins rather than nuclear spins. Depending on the ESR experiment, researchers may add a molecular probe with a stable unpaired electron to a sample or label a molecule such as a protein directly.

The ESR techniques and analyses developed by Freed “have led to an extremely powerful methodology for the study of complex molecular dynamics in liquids that is virtually unrivaled and will continue to serve as the basis for future studies in chemistry, biology, and physics,” says Benjamin Widom, one of Freed’s faculty colleagues at Cornell.

Freed’s theoretical analysis of ESR spectra showed in particular that ESR signals are very sensitive to the microscopic details of molecular motions in liquids. In early work, Freed found that simple Brownian motion modeling was inadequate to describe diffusion of molecular probes in a variety of liquids. Instead, more complex models involving dynamic solvent cage structures around solutes were necessary to explain solution behavior. Freed and colleagues were also able to elucidate the details of the cages and how they changed over time.

Freed’s lab has further studied microscopic ordering and dynamics in liquid crystals. That work includes the study of phospholipid membranes—considered a type of liquid crystal—and how the addition of peptides and proteins affects membrane dynamics. Freed turned to such biological systems in 2001, when he founded the National Biomedical Center for Advanced Electron Spin Resonance Technology, which is funded by the National Institutes of Health. His most recent work in the area involves studying the initial steps of how a virus fuses with a membrane.

Freed, 75, counts among his most meaningful awards the 1997 ACS Irving Langmuir Award in Chemical Physics and this year’s Hildebrand Award, because they validate his unique work on the chemical physics of liquids, he says. He is also the only ESR expert to receive the International Society of Magnetic Resonance Prize for research performed in the past 50 years.

Freed will present the award address before the Division of Physical Chemistry.

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