Two- and Three-Dimensional 13C-17O Heteronuclear Correlation NMR Spectroscopy for Studying Organic and Biological Solids

We report two- and three-dimensional (2D and 3D) C-13-O-17 heteronuclear correlation solid-state NMR experiments under magic-angle spinning (MAS) conditions. These experiments utilize the D-RINEPT (Dipolar-mediated Refocused Insensitive Nuclei Enhanced by Polarization Transfer) scheme with symmetry-based SR4(1)(2), recoupling blocks for coherence transfer between C-13 and O-17 nuclei. First, a 2D O-17 -> C-13 correlation experiment was performed for the [1-C-13, O-17]-Gly/Gly center dot HCl cocrystal and [U-C-13, 1-O-17]-alpha/beta-D-glucose samples. Second, a 2D O-17 -> C-13 MAD-RINEPT correlation experiment where the indirect dimension incorporates the multiple-quantum MAS (MAMAS) scheme was tested for obtaining isotropic O-17 resolution with [U-C-13, 1-O-17]-alpha/beta-D-glucose. Third, a new 3D O-17 -> C-13 -> C-13 correlation experiment was demonstrated where O-17 -> C-13 and C-13 -> C-13 correlations are achieved by D-RINEPT and DARR (Dipolar Assisted Rotational Resonance) sequences, respectively (thus termed as a 3D D-RINEPT/DARR OCC experiment). This new 3D O-17 NMR experiment is implemented with the aim for site-resolved solid-state O-17 NMR studies.

Automated summary

This study presents two- and three-dimensional C-13-O-17 heteronuclear correlation solid-state NMR experiments under magic-angle spinning (MAS) conditions. The experiments were performed on different samples using various schemes to achieve coherence transfer between C-13 and O-17 nuclei. This new 3D O-17 NMR experiment aims for site-resolved solid-state O-17 NMR studies, demonstrating successful correlations between O-17, C-13, and C-13 nuclei.