John Bartmess Professor Organic and Computational       Chemistry Gas phase ion chemistry; mass spectrometry; molecular orbital calculations B.S., Rice University (1970) Ph.D., Northwestern University (1975)
E-mail: bartmess@ion.chem.utk.edu 609 Buehler Hall   ·   Telephone: 865-974-6578 Representative publications   ·   Biographical sketch   ·   Group Web page

Research

What role does solvation pay in determining the course of reaction mechanisms? The majority of chemical reactions are run with some solvent present, yet there is a strong tendency for chemists, when postulating mechanisms, to consider only the intrinsic structure of the reactants. Chemists do not have the simple mental picture of the "structure" of the solvation about the reactants, that corresponds to the valence bond structure of the reactants themselves. There is a tendency to regard solvation as a minor perturbation, something that only holds the reactants up off the bottom of the flask, unless we are forced to do otherwise by the facts.

My research is directed toward separating these effects of solvation and intrinsic structure, principally by examining the gas phase analogs of "well-known" condensed phase reactions, using ion cyclotron resonance (ICR) spectrometry. ICR is a form of mass spectrometry which traps gas phase ions in a magnetic field for several seconds, so that the ions can react with neutral molecules in a bimolecular fashion to give product ions. Both positive and negative ions can be trapped; we have concentrated on the less known negative ions so far. A principal area of research has been measuring Bronsted acidities, where a scale of gas phase acidities of both organic and inorganic structures has been constructed over a 100 kcal/mole range. Other topics of current interest include the E2/Elcb elimination reaction, and the effect that hydrogen bonding a single molecule of solvent to the ion has on its reactivity. The analytical aspects of ICR spectrometry involving instrumental development and molecular structural determination are under investigation. Molecular orbital calculations are used as an additional tool, to evaluate the experimental data obtained from the gas phase work. Solution calorimetry is used to relate the gaseous thermochemical data obtained from the ICR work to the condensed phase, and obtain single ion heats of solvation.

Representative publications

The gas phase acidities of long chain alcohols. P.R. Higgins and J.E. Bartmess, Int. J. Mass Spectrom. Ion Proc. 175, 71 (1998).

Competitive reactivity as a probe for reaction coordinates in gas phase ion-molecule chemistry. R.W. Holman, T.L. Sumpter, J. Farrar, K. Weigel, and J.E. Bartmess, J. Phys. Org. Chem. 10, 585 (1997).

A screening method for ranking and scoring chemicals by potential human health and environmental impacts. M.B. Swanson, G.A. Davis, L.E. Kincaid, T.W. Schultz, J.E. Bartmess, S.L. Jones, and E.L. George, Environ. Tox. Chem. 16, 372 (1997).

Ion-molecule chemistry. The role of intrinsic structure, solvation, and counterions. J.E. Bartmess in Advances in Gas Phase Ion Chemistry Vol. 2, N.G. Adams and L.M. Babcock, eds. (JAI Press, Greenwich, CT: 1995).

The thermodynamics of the electron and the proton. J.E. Bartmess, J. Phys. Chem. 98 6420 (1994).

Biographical sketch

Professor Bartmess joined the Tennessee faculty in 1984. He received his Ph.D. in chemistry from Northwestern University in 1975 under the direction of Dr. Frederick Bordwell. Following his Ph.D., he performed postdoctoral research with Robert McIver at the University of California at Irvine and was a member of the chemistry faculty at Indiana University.