NMR on Macroscopically Oriented Lyotropic Systems

Abstract

Solid state NMR spectroscopy is extremely useful for investigations of many different aspects of lyotropic liquid crystalline phases, as can be inferred from the very large number of papers published on this matter over the last twenty years (see Web of SCI). Just to mention a few important examples, NMR methods have been shown to be informative and rapid for convenient determinations of phase equilibria as well as of phase structures [1], in particular the structure of the so called cubic phases. Information about solubilization, extent of hydration, orientation of various molecules and the dynamics of the lyotropic phase can be easily obtained. Here, we confine ourselves to NMR investigations of translational diffusion of water and lipids in macroscopically aligned lyotropic liquid crystals. We also put some emphasis on how to get a good orientation of a lamellar phase between glass plates. This is crucial for the use of pulsed-field gradient (pfg) NMR and it is also of importance for other solid-state NMR techniques as well as for various other methods, such as X-ray and neutron diffraction, fluorescence recovery after photo-bleaching (FRAP), linear and circular dichroism and electron spin resonance. Finally, we present some of our recent results on macroscopically oriented systems.