## LSU Historical Dissertations and Theses

1989

Dissertation

#### Degree Name

Doctor of Philosophy (PhD)

Chemistry

Leslie G. Butler

#### Abstract

This dissertation is the first application of a Karplus-type relationship to solid-state deuterium NMR spectroscopy. In particular zero-field high-resolution deuterium adiabatic demagnetization in the laboratory frame (ADLF) spectroscopy has been used to distinguish between two inequivalent deuterium positions in alpha substituted arylacetic acids. High resolution spectra with linewidths of 1-2 kHz were observed and have been used successfully to document the inequivalent positions both by single and double transition spectra. Further, small applied fields, inducing Zeeman splitting, have proven the deuterons observed to be from the transition frequencies of two different deuterons. Individual spectra are shown for all compounds included in this study. The quadrupole coupling constants, e$\sp2$q$\sb{\rm zz}$Q/h, were calculated from spectral data. Torsion angle data were calculated from single crystal X-ray analysis. The Karplus equation, a method of examining three bond J coupling in solution NMR spectroscopy has been adapted for use in solid-state zero-field deuterium NMR spectroscopy for the H-C-C-X torsion angle where X is an heavy atom: e$\sp2$q$\sb{\rm zz}$Q/h = A $-$ B cos($\theta$) $-$ C cos(2$\theta$) $-$ D sin(2$\phi$). The parameters, A, C, and D are derived from experimental data; B was obtained from molecular orbital calculations. The quadrupole coupling constants and torsion angles, $\sp2$H-C$\sb{\rm alpha}$-C$\sb{\rm acid}$-OH($\theta$) and C$\sb{\rm ortho}$-C$\sb{\rm ring}$-C$\sb{\rm alpha}$-C$\sb{\rm acid}$($\phi$), were calculated from experimental data. Two and three dimensional graphs have been generated. From the three dimensional graphs, the torsion angles for an arylacetic acid without a crystal structure have been predicted based upon the results of ADLF spectroscopy and the Karplus-type relationship.

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