title: Fast Magic-Angle Spinning Three-Dimensional NMR Experiment for Simultaneously Probing H-H and N-H Proximities in Solids.
abstract: A fast magic-angle spinning (MAS, 70 kHz) solid-state NMR experiment is presented that combines1H Double-Quantum (DQ) and14N-1H HMQC (Heteronuclear Multiple-Quantum Coherence) pulse-sequence elements, so as to simultaneously probe H-H and N-H proximities in molecular solids. The proposed experiment can be employed in both two-dimensional (2D) and three-dimensional (3D) versions: first, a 2D14N HMQC-filtered1H-DQ experiment provides specific DQ-SQ correlation peaks for proton pairs that are in close proximities to the nitrogen sites, thereby achieving spectral filtration. Second, a proton-detected three-dimensional (3D)1H(DQ)-14N(SQ)-1H(SQ) experiment correlates1H(DQ)-1H(SQ) chemical shifts with14N shifts such that longer range N···H-H correlations are observed between protons and nitrogen atoms with internuclear NH distances exceeding 3 Å. Both 2D and 3D versions of the proposed experiment are demonstrated for an amino acid hydrochloride salt, l-histidine·HCl·H2O, and a DNA nucleoside, guanosine·2H2O. In the latter case, the achieved spectral filtration ensures that DQ cross peaks are only observed for guanine NH and CH81H resonances and not ribose and water1H resonances, thus providing insight into the changes in the solid-state structure of this hydrate that occur over time; significant changes are observed in the NH and NH21H chemical shifts as compared to the freshly recrystallized sample previously studied by Reddy et al., Cryst. Growth Des. 2015, 15, 5945.
authors: G N Manjunatha
authors: GN
authors: Reddy
authors: JEOL RESONANCE Inc. , Musashino, Akishima, Tokyo 196-8558, Japan.|RIKEN CLST-JEOL Collaboration Centre , Yokohama, Kanagawa 230-0045, Japan.
authors: Michal
authors: M
authors: Malon
authors: Andrew
authors: A
authors: Marsh
authors: JEOL RESONANCE Inc. , Musashino, Akishima, Tokyo 196-8558, Japan.|RIKEN CLST-JEOL Collaboration Centre , Yokohama, Kanagawa 230-0045, Japan.
authors: Yusuke
authors: Y
authors: Nishiyama
authors: Steven P
authors: SP
authors: Brown