Many NMR experiments are designed so that 1JCH values are measured from peak separation in either the 1H or 13C dimension of a two-dimensional 1H-13C correlation experiment. However, the measured 1JCH values suffer in accuracy when second-order effects are present. These effects are prominent in carbohydrates, nucleic acids and amino acid side-chains, where many 1H's are strongly coupled. These values can lead to errors in structural analysis when used to measure residual dipolar couplings. Nevertheless, the literature is replete with experiments designed to yield  1JCH values that are not compared to those measured using different methods. We demonstrate consistent analytical methods that yield accurate 1JCH values. We also describe previously unreported long range 1H-13C J couplings that will help define three-dimensional carbohydrate structure.

Accurate J coupling measurements for reliable carbohydrate structures

241st National Meeting (2011)

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