High-resolution NMR on cubic lyotropic liquid crystalline phases

A cubic liquid crystalline phase composed of monooleoylglycerol (monoolein, MO) and 2H2O was investigated by high-resolution NMR. With magic angle spinning (MAS) all orientation-dependent line-broadening was averaged out and nearly liquid-like NMR spectra were observed. 1H- and 13C-spectra are presented for samples with a cubic structure. The narrow lines allow the application of standard two-dimensional NMR experiments. Structural investigations may be conveniently performed by these NMR methods and they can also provide insight into lipid/water interaction at the molecular level. A slow exchange of water protons with the OH-protons of MO, as well as spatial proximity of water to non-exchangeable protons of the glycerol moiety was observed. Cubic liquid crystalline phases may provide model systems for studies of biologically active molecules using MAS-NMR techniques.