Wasylishen, Roderick E.Professor Office: E3-24, Chemistry Centre |
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NMR spectroscopy is one of the most important and versatile techniques for characterizing the structure and dynamics of molecules. Traditionally, high-resolution NMR studies have been confined to isotropic liquid samples because solids have a reputation of yielding broad featureless NMR spectra. Over the past twenty years, several ingenious experimental techniques have been devised to eliminate the line-width problem. There are many advantages of using NMR to investigate solid materials and much of our research has involved exploring applications of solid-state NMR. We have been particularly interested in measuring the orientation dependence of the NMR chemical shifts, spin-spin coupling constants and quadrupolar coupling constants using a variety of techniques such as single-crystal NMR. In addition to experimentally measuring these fundamental NMR parameters, their interpretation in terms of electronic and molecular structure has been of considerable interest. Typically, our experimental data are complemented by state-of-the-art ab-initio molecular orbital calculations. The goal of this research is to obtain a better understanding of magnetic shielding, spin-spin coupling and electric field gradient tensors.
Other interests include applications of new multi-pulse NMR techniques, e.g., those designed to recouple both homonuclear and heteronuclear dipolar interactions and techniques designed to obtain high-resolution NMR spectra of half-integer quadrupolar nuclei such as the MQMAS experiment. We are also actively involved is using the highest magnetic fields available for NMR studies to investigate important quadrupolar nuclei with small magnetic moments (e.g. 25Mg, 35/37Cl, 53Cr, 91Zr, 95Mo). Although our studies have focused on traditional inorganic systems, we tackle a wide range of diverse solid materials including paramagnetic systems, surfaces and porous materials. Using spin-exchange optical pumping techniques which utilize a 60 watt-diode laser system, 129Xe nuclear spin population enhancements of approximately 104 are being realized. This makes 129Xe NMR an ideal technique for investigating the latter materials.
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Phosphorus-31 NMR spectrum of a phosphole tetramer, obtained at an applied magnetic field of 4.7 T with the sample spinning at the magic angle at a rage of 2 kHz. The asterisk indicates the isotropic peak while the remaining peaks are spinning sidebands
T. Ueda, T. Eguchi, N. Nakamura and R.E. Wasylishen, "High-Pressure 129Xe NMR Study of Xenon Confined in the Nanochannels of Solid (±)-[Co(en)3]Cl3", J. Phys. Chem. B, 2003, 107, 180-185.
M.A.M. Forgeron, D.L. Bryce, R.E. Wasylishen and R. Rösler, "A Multinuclear Magnetic Resonance Investigation of Hexamethylborazine", J. Phys. Chem. A, 2003, 107, 726-735.
D.L. Bryce and R.E. Wasylishen, "Evaluation of the Influence of Anisotropic Indirect Nuclear Sin-Spin Coupling Tensors on Effective Residual Dipolar Couplings for Model Peptides", J. Biomol. NMR, 2003, 25, 73-78.
K. Eichele, R.E. Wasylishen, J.F. Corrigan, N.J. Taylor, A.J. Carty, K.W. Feindel and G.M. Bernard, "Phosphorus chemical shift tensors of phosphido ligands is ruthenium carbonyl compounds. 31P NMR spectroscopy of single-crystal and powder samples and ab initio calculations", J. Am. Chem. Soc., 2002, 124, 1541-1552.
R.E. Wasylishen and D.L. Bryce, "A revised experimental absolute magnetic shielding scale for oxygen", J. Chem. Phys., 2002, 117, 10061-10066.
J. Vaara, J. Jokisaari, R.E. Wasylishen, D.L. Bryce, "Spin-spin coupling tensors as determined by experiment and computational chemistry", Prog. Nucl. Magn. Reson. Spectrosc., 2002, 41, 233-304.
M. Gee, R.E. Wasylishen, P.J. Ragogna, N. Burford and R. McDonald, "Characterization of Indirect 31P-31P Spin-Spin Coupling and Phosphorus Chemical Shift Tensors in Pentaphenylphosphinophosphonium Tetrachlorogallate, [Ph3P-PPh2][GaCl4]", Can. J. Chem., 2002, 80, 1488-1500.