Solid-state 17O NMR study of the electric-field-gradient and chemical shielding tensors in polycrystalline γ-glycine

We report the first experimental determination of the carboxylate oxygen electric-field-gradient (EFG) and chemical shielding (CS) tensors in polycrystalline γ-glycine. Analysis of magic-angle spinning (MAS) and stationary 17O NMR spectra of [17O]-γ-glycine obtained at 9.4, 14.1, 16.4, and 18.8 T yields the magnitudes of the 17O EFG and CS tensors and the relative orientations between the two tensors. Extensive quantum chemical calculations at both the restricted Hartree-Fock and density functional levels have been performed to present the absolute tensor orientations in term of the molecular frame. We have demonstrated that 17O NMR tensor information could be unambiguously derived by the multiple field analyses of stationary 17O NMR spectra.