Merging concepts from liquid-state and solid-state NMR spectroscopy for the investigation of supra- and biomolecular systems

After the fields of liquid- and solid-state NMR spectroscopy have developed largely independently of each other over the past 50 years, materials of current interest call for new approaches which combine and merge spectroscopic techniques from either side. A particular possibility to promote NMR spectroscopy into this direction is provided by magic-angle sample spinning (MAS), which can be performed either at high speeds in solid-state NMR or at moderate speeds in combination with high-resolution NMR. In this way, new NMR methods and experiments have recently been developed, as will be discussed in this review. In solid-state NMR, new and versatile experiments are based on coherent spin-states and coherent transfer mechanisms, provided that fast MAS ensures efficient averaging of anisotropic interactions, and recoupling schemes selectively re-introduce the interactions of interest. In high-resolution NMR, MAS can be borrowed from solid-state NMR in order to ensure sufficient spectral resolution for samples with residual anisotropies or heterogeneities (so-called HRMAS). In such HRMAS studies, recoupling techniques become applicable and provide fully quantitative information on molecular structure and dynamics.