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Suppressing one‐bond homonuclear 13 C, 13 C scalar couplings in the J‐HMBC NMR experiment: application to 13 C site‐specifically labeled oligosaccharides
Author(s) -
Pendrill Robert,
Sørensen Ole W.,
Widmalm Göran
Publication year - 2014
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.4038
Subject(s) - homonuclear molecule , chemistry , heteronuclear molecule , coupling constant , carbon 13 , pulse sequence , spectral line , molecule , analytical chemistry (journal) , nmr spectra database , j coupling , carbon 13 nmr , nuclear magnetic resonance , nuclear magnetic resonance spectroscopy , stereochemistry , computational chemistry , organic chemistry , physics , quantum mechanics , particle physics , astronomy
Site‐specific 13 C isotope labeling is a useful approach that allows for the measurement of homonuclear 13 C, 13 C coupling constants. For three site‐specifically labeled oligosaccharides, it is demonstrated that using the J‐HMBC experiment for measuring heteronuclear long‐range coupling constants is problematical for the carbons adjacent to the spin label. By incorporating either a selective inversion pulse or a constant‐time element in the pulse sequence, the interference from one‐bond 13 C, 13 C scalar couplings is suppressed, allowing the coupling constants of interest to be measured without complications. Experimental spectra are compared with spectra of a nonlabeled compound as well as with simulated spectra. The work extends the use of the J‐HMBC experiments to site‐specifically labeled molecules, thereby increasing the number of coupling constants that can be obtained from a single preparation of a molecule. Copyright © 2014 John Wiley & Sons, Ltd.