Long-range carbon-proton coupling constants: application to conformational studies of oligosaccharides
Related Experiment Video
Updated: Oct 29, 2026

Using a Cyclic Ion Mobility Spectrometer for Tandem Ion Mobility Experiments
Published on: January 20, 2022
B Mulloy1, T A Frenkiel, D B Davies
1National Institute for Biological Standards and Control, Herts, Great Britain.
Abstract:
3JC,H values have been measured using selective 2D heteronuclear J-resolved n.m.r. spectroscopy for the COCH fragment in various carbohydrates. Measurements on model compounds have been used to characterise a Karplus-type relationship between 3JCOCH and dihedral angles in sugar. The 3JC,H values have also been measured for C-2'-O-2'-C-1-H-1 of sucrose and the sucrose residues in raffinose, stachyose, and melezitose. These values are similar to each other for solutions in D2O and (CD3)2SO and are little affected by the change in solvent, but differ from those predicted from the crystal conformations. The method has been used to correct some assignments in the published 13C-n.m.r. spectrum of melezitose.
Related Concept Videos
Chemistry of Carbohydrates
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Spin–Spin Coupling Constant: Overview
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Spin–Spin Coupling: One-Bond Coupling
¹H NMR: Long-Range Coupling
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR

