Constant-time 2D and 3D through-bond correlation NMR spectroscopy of solids under 60 kHz MAS

Journal Article · Thu Jan 21 00:00:00 EST 2016 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4940029· OSTI ID:22493661

Zhang, Rongchun; Ramamoorthy, Ayyalusamy ^[1]

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1. Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109-1055 (United States)

Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and the use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D {sup 1}H/{sup 13}C/{sup 1}H chemical shift correlation spectrum by incorporating an additional cross-polarization period in the CTUC-COSY pulse sequence to enable proton chemical shift evolution and proton detection in the incrementable t{sub 1} and t{sub 3} periods, respectively. In addition to through-space and through-bond {sup 13}C/{sup 1}H and {sup 13}C/{sup 13}C chemical shift correlations, the 3D {sup 1}H/{sup 13}C/{sup 1}H experiment also provides a COSY-type {sup 1}H/{sup 1}H chemical shift correlation spectrum, where only the chemical shifts of those protons, which are bonded to two neighboring carbons, are correlated. By extracting 2D F1/F3 slices ({sup 1}H/{sup 1}H chemical shift correlation spectrum) at different {sup 13}C chemical shift frequencies from the 3D {sup 1}H/{sup 13}C/{sup 1}H spectrum, resonances of proton atoms located close to a specific carbon atom can be identified. Overall, the through-bond and through-space homonuclear/heteronuclear proximities determined from the 3D {sup 1}H/{sup 13}C/{sup 1}H experiment would be useful to study the structure and dynamics of a variety of chemical and biological solids.

• OSTI ID: 22493661
• Journal Information: Journal of Chemical Physics, Vol. 144, Issue 3; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ABSORPTION SPECTROSCOPY
ATOMS
CARBON
CARBON 13
CHEMICAL SHIFT
CORRELATIONS
COSY STORAGE RING
DECOUPLING
HYDROGEN 1
KHZ RANGE
MOLECULES
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
POLARIZATION
PROTON DETECTION
PROTONS
RADIOWAVE RADIATION
SOLIDS
SPIN-SPIN RELAXATION