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

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In this award, funded by the Experimental Physical Chemistry Program of the Division of Chemistry, Professor Peter B. Armentrout of the University of Utah, his post-doctoral fellows, graduate, and undergraduate students will be supported to study gas-phase organometallic and biological ion chemistry and chemical dynamics. The work utilizes guided ion beam tandem mass spectrometry (GIBMS). Detailed kinetic and thermodynamic data are obtained by accurately measuring absolute reaction probabilities at thermal and hyperthermal energies followed by a detailed analysis of the kinetic energy dependent cross sections obtained. Four related areas of chemical interactions are being studied. First, the chemistry of 3rd row transition metal ions designed to measure bond dissociation energies (BDEs) with various hydrogen, oxygen, and carbon ligands will be pursued. State-specific chemistry of 2nd and 3rd row TM ions will be studied with an emphasis on a quantitative evaluation of spin-orbit coupling (SOC) effects. Second, solvation energies of multiply charged metal ions will be quantitatively assessed and methods for explicit quantification of the potential energy surface for charge separation channels in such systems will be developed. Third, BDEs between metal ions and biologically relevant molecules will be explored and expanded to the energetics for decomposition of protonated peptides. Fourth, analysis of threshold collision-induced dissociation (TCID) of increasingly large and complex systems involving multiple competitive and sequential pathways will continue to be developed.The thermodynamic information acquired in these studies is of relevance to surface science, organometallic chemistry, catalysis, sustainable energy, environmental and biological systems, as well as health. For example, one system of particular interest is elucidation of the energetics for the deamidation of asparagine, believed to be a major molecular process contributing to aging. A key component of this research program is its educational objectives, which involve a number of students (undergraduate, graduate, and postdoctoral) who are fully engaged in all aspects of the research program. The means used to analyze the data are made freely available and are presently used by dozens of laboratories worldwide.