Residual dipolar couplings (RDCs) are amongst the most powerful NMR parameters for organic structure elucidation. In order to maximize their effectiveness in increasingly complex cases such as flexible compounds, a maximum of RDCs between nuclei sampling a large distribution of orientations is needed, including sign information. For this, the easily accessible one-bond 1H–13C RDCs alone often fall short. Long-range 1H–1H RDCs are both abundant and typically sample highly complementary orientations, but accessing them in a sign-sensitive way has been severely obstructed due to the overflow of 1H–1H couplings. Here, we present a generally applicable strategy that allows the measurement of a large number of 1H–1H RDCs, including their signs, which is based on a combination of an improved PSYCHEDELIC method and a new selective constant-time β-COSY experiment. The potential of 1H–1H RDCs to better determine molecular alignment and to discriminate between enantiomers and diastereomers is demonstrated.
Probing Long-Range Anisotropic Interactions: a General and Sign-Sensitive Strategy to Measure 1H–1H Residual Dipolar Couplings as a Key Advance for Organic Structure Determination
Di Pietro M. E.;
2020-01-01
Abstract
Residual dipolar couplings (RDCs) are amongst the most powerful NMR parameters for organic structure elucidation. In order to maximize their effectiveness in increasingly complex cases such as flexible compounds, a maximum of RDCs between nuclei sampling a large distribution of orientations is needed, including sign information. For this, the easily accessible one-bond 1H–13C RDCs alone often fall short. Long-range 1H–1H RDCs are both abundant and typically sample highly complementary orientations, but accessing them in a sign-sensitive way has been severely obstructed due to the overflow of 1H–1H couplings. Here, we present a generally applicable strategy that allows the measurement of a large number of 1H–1H RDCs, including their signs, which is based on a combination of an improved PSYCHEDELIC method and a new selective constant-time β-COSY experiment. The potential of 1H–1H RDCs to better determine molecular alignment and to discriminate between enantiomers and diastereomers is demonstrated.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
