Transient Intermediates of Chemical Reactions

University Of Washington, Seattle WA

Investigators

Abstract

Professor Frantisek Turecek, of the Department of Chemistry at the University of Washington, is supported by the Organic and Macromolecular Chemistry Program for his research on transient intermediates of chemical reactions in the gas phase. The objectives of the proposed research are to (1) generate in the gas phase elusive and highly reactive radicals relevant to the high-energy chemistry of peptides, nucleic acids, and organometallic compounds, (2) investigate the stabilities, dissociation kinetics, and photoexcitation of the transient species, and (3) use high-level quantum chemistry calculations combined with RRKM theory to obtain relative, dissociation, and activation energies for the transient intermediates and gauge the dissociation kinetics. The basic experimental method is neutralization-reionization mass spectrometry (NRMS), using a "non-chemical" means to generate transient species. In NRMS the short interaction time between ion and target results in maintaining both bond connectivity and geometry in the nascent neutral species generated. New methods are proposed to extend the NRMS methodologies to study transient intermediates from polar compounds and allow for measurements of fast dissociations. The potential impact of these studies is in providing new insights into the complex chemistries of highly reactive polyatomic species that are formed transiently by high-energy processes. These studies, complemented by computational analyses, address the stabilities and reactivity of these transient intermediates, shedding light on the fundamental events that occur during high-energy processes. The reaction of atmospheric oxygen with molecules containing sulfur occurs on a scale of one million tons per year globally making it of considerable environmental importance. With the support of the Organic and Macromolecular Chemistry Program Professor Frantisek Turecek will generate and study in the laboratory the many products from these and related reactions. In addition to studying these smaller molecules that are of great significance to the environment and sustaining life on this planet, Professor Turecek's research focuses on larger molecular systems relevant to nucleic bases. Radicals derived from nucleic bases are presumed to occur as short lifetime species that can cause the modification of RNA and DNA, especially in radiation damage caused by exposure to sunlight, background radiation, or other high-energy processes. Characterization of transient intermediates represents a formidable challenge to the experimental and theoretical methods of chemistry. This inquiry into the processes and dynamics of transient intermediates has the potential for practical usefulness in peptide sequencing.