Magnetic Resonance Studies of Molecular Structure and Dynamics

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Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) are closely related techniques which reveal molecular structure and composition by detecting the response of nuclear "bar magnets" to radiofrequency waves in the presence of a strong applied magnetic field. The proposed research will use modern NMR and MRI techniques to provide insights into important problems in structural chemistry, materials science and plant science. Our approach to research and graduate student training consists of fundamental aspects as well as more applied ones. The goal of the fundamental research outlined in this proposal is to gain a better understanding of the relationship between the parameters that one measures in an NMR experiment and molecular structure. We will take advantage of the fact that NMR studies of solid materials provide one with an opportunity to characterize the orientation dependence of the observed magnetic shielding, rather than just their average values. For example, solid-state (SS) H-1 NMR will be used to better characterize hydrogen magnetic shielding of transition metal hydrides and dihydrogen complexes that play a central role in catalytic inorganic and organometallic chemistry. The applied aspects range from using SS NMR to investigate the molecules present in forest floor samples and their relationship to forest health to building an apparatus to produce enriched para-hydrogen so that we can use hyperpolarized NMR to study the mechanism of important organometallic reactions. We will continue to take advantage of the National Ultrahigh-Field NMR Facility for Solids in Ottawa to explore the potential of NMR in studying "difficult" quadrupolar nuclei that have been little explored because of their poor receptivities (e.g., challenging isotopes, such as As-75, that are biologically relevant and Ir-193 that is very important in organometallic chemistry). We will continue exploring applications of micro-MRI which has proven important for research and student training.