Applications of nuclear magnetic resonance spectroscopy in organic and biological chemistry

Abstract

Monocyclic derivatives of hydroxylamines were synthesised to investigate their conformations and conformational rate processes. Derivatives of 1,4,2-oxathiazine(1-oxa-4-thia-2-azacyclohexane) were prepared, their conformational equilibria investigated and their rates of nitrogen and ring inversion measured. N-carbethoxy-1-oxa-2-azacyclooctane was prepared and reduced to N—methyl-1-oxa-2-azacyclooctane, whose nitrogen inversion rate was. measured. N-carbethoxy-5,5-dimethyl-1-oxa- 2-azacyclooctane and N-carbethoxy-6,6-dimethyl-1-oxa-2-azacyclononane were also prepared. Treatment of these compounds led to the formation of N-carbethoxy-2-(aminohydroxy)-3,3- dimethylhexane and N-carbethoxy-2- (aminohydroxy)-4,4-dimethylheptane respectively instead of the N-methyl derivatives. Other attempts to make the N-methyl derivatives also failed.

An investigation of aqueous lanthanide shift reagents for 23Na and 39K was undertaken. The best combinations were found with tripolyphosphate as the ligand in combination with Dysprosium or Terbium. Isotropic hyperfine shifts of up to ca 40 ppm (23Na) and ca 13 ppm (39K) are reported. The shift reagents were used to investigate intracellular Na+ and K+ in cellular systems. A quantitation of intracellular 39K in human erythrocytes Is reported. The use of these shift reagents in combination with large unilamellar vesicles of egg-yolk phosphatidylcholine is demonstrated to be a viable technique for measuring ionophore mediated membrane transport of Na+ and K+. The monensin mediated transport of Na+ was studied and shown to be first order in monensln. The transport was inhibited by the substrate itself, In a concentration dependent manner. Two related [15]-crown-5 derivatives were also investigated. The result indicated that anionic ionophores are more efficient in membrane transport than neutral ionophores.