Measurement of carbon-proton dipolar couplings in liquid crystals by local dipolar field NMR spectroscopy

Journal Article · Thu Nov 28 04:00:00 EST 1996 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/jp962023z· OSTI ID:437406

Caldarelli, S; Emsley, L ^[1]; Hong, M; Pines, A ^[2]

---

1. Ecole Normale Superieure de Lyon (France)
2. Lawrence Berkeley Lab., CA (United States)

The performance of several different two-dimensional NMR methods for the measurement of carbon-proton dipolar couplings in liquid crystalline phases is analyzed. Proton-detected local field spectroscopy allows the measurements of short range C-H couplings, which correspond to directly bond pairs, by direct inspection of the spectra. Off magic angle (OMAS) spinning techniques can be applied to anisotropic phases that can be oriented mechanically at an angle to the magnetic field, such as nematic phases. The consequent scaling of the chemical shift anisotropy and dipolar couplings can be used to resolve otherwise overlapping resonances. Moreover, an estimate of the accuracy of the technique can be achieved by performing a series of OMAS experiments with different sample orientations. 31 refs., 7 figs., 2 tabs.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 437406
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 48 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
CARBON
COUPLING
LIQUID CRYSTALS
MAGNETIC PROPERTIES
MEASURING METHODS
NMR SPECTRA
PROTONS