Suppressing one‐bond homonuclear 13C,13C scalar couplings in the J‐HMBC NMR experiment: application to 13C site‐specifically labeled oligosaccharides |
| |
Authors: | Robert Pendrill Ole W Sørensen Göran Widmalm |
| |
Institution: | Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, , S‐106 91 Stockholm, Sweden |
| |
Abstract: | Site‐specific 13C isotope labeling is a useful approach that allows for the measurement of homonuclear 13C,13C 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 13C,13C 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. |
| |
Keywords: | NMR 1H 13C J‐HMBC oligosaccharide heteronuclear long‐range coupling constants site‐specific labeling |
|
|