Simplified nuclear magnetic resonance (NMR) spectra of heteronuclear dipolar couplings for molecules in an anisotropic environment, such as liquid crystals and lipids, are obtained by proton-detected local-field spectroscopy. The distance-dependent dipolar interactions between spins of magnetically active nuclei can be determined directly from the spectrum because many-body effects that complicate conventional dipolar NMR spectra are avoided by selectively probing local fields produced by rare spins at the location of abundant spins. We employ the technique to resolve the carbon-proton dipolar couplings of benzene dissolved in a nematic liquid crystal and to measure phosphorus-proton couplings in lecithin in the L(alpha) phase to obtain constraints on the phosphocholine headgroup structure.
Giovanni Boero, Fabio Donati, Soyoung Oh
Rolf Gruetter, Andrea Capozzi, Jean-Noël Hyacinthe, Thanh Phong Kevin Lê, Emma Linnea Wiström
David Lyndon Emsley, Federico De Biasi, Máté Visegrádi, Michael Allan Hope