Fluorine as an NMR probe for structural studies of chemical and biological systems

Applications of fluorine NMR to probe long-range interactions in rigid organic molecules, namely cubanes, and to study structures and dynamics of proteins and other biological systems, are presented. 19F NMR parameters, especially long-range coupling constants are shown to reveal intrinsic features of the molecules. Correlations between long-range (more than three-bond) couplings involving fluorine and other chemical and physico-chemical properties of the compounds are demonstrated, and examples of unusual couplings which cannot be explained by existing theories of ‘through-bond’ and ‘through-space’ mechanisms are discussed. Recent applications of fluorine labeling of aromatic and aliphatic amino acids in investigating protein structures and dynamics are highlighted. The potential of using 19F NMR parameters, such as large spin–spin coupling constants observed for organic compounds, for structural analysis of biological macromolecules is outlined.