Thermochemistry of Metal-Ligand Bonds (Singly and Multiply Charged) and Protonated Peptides

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In this award, funded by the Chemical Structure, Dynamics and Mechanisms A (CSDM-A) Program of the Division of Chemistry, Professor Peter B. Armentrout of the Department of Chemistry of the University of Utah and graduate student researchers are studying the reactivity of electrically-charged species (ions) with neutral molecules. The chemical systems being studied include transistion metal ions such as zinc (Zn2+), cadmium (Cd2+) and tungsten (W+), and biologically relevant molecules such as the amino acids asparagine, glycine and glutamine. From these experiments, they obtain information about the changes in energy between reactant and product molecules(thermochemistry) as well as information about the speed with which these reactions take place (kinetics). Such quantitative information is of use to a broad range of scientific endeavors. Professor Armentrout has made an evolving data analysis program (CRUNCH), freely available to groups worldwide. This program enhances infrastructure for research. This project involves many students(undergraduate and graduate) in all aspects of research. Students design and construct instrumentation, interface data acquisition equipment, propose and conduct experiments, run computational studies, analyze experimental and theoretical results, and prepare manuscripts. Opportunities to conduct research at a user facility in the Netherlands broaden the students' research and cultural experience further. Outreach efforts by the Professor Armentrout include participation in the STEM for U Week in which he visits several K-12 classes to present scientific content and career possibilities.Prof. Armentrout and his graduate students carry out a series of experiments, exploring the reactivity of cations with neutral reaction partners, using their guided ion beam tandem mass spectrometer (GIBMS) instruments. Studies include: (1) electronic state-specific measurements of transition metal cation reactivity, with an emphasis on quantitative evaluation of spin-orbit effects on chemical reactivity; (2) measurements of solvation energies of multiply charged metal ions, including explicit quantification of the potential energy surface for charge separation channels, emphasizing environmentally and biologically important examples; (3) binding studies of biologically-relevant molecules to metal cations and protonated systems, with an emphasis on deamidation of asparagine (believed to be a major molecular process in aging); (4) spectroscopic studies of species formed in carbon-hydrogen bond activation reactions by transition metal cations and of metallated biologically relevant molecules; and (5) theoretical work to complement all of the experimental studies in (1) - (4). The research is interdisciplinary, utilizing state-of-the-art physical and analytical methods. Students receiving training in Professor Armentrout's laboratory have gone on to positions in academia and industry.