Conformation‐dependent 13C chemical shifts: A new means of conformational characterization as obtained by high‐resolution solid‐state 13C NMR

Abstract A survey of recent high‐resolution solid‐state 13 C NMR studies is given to illustrate how and to what extent 13 C chemical shifts of a variety of molecular systems are displaced upon conformational changes. Examples are taken from studies of alkanes, polysaccharides, polypeptides, and naturally occurring and synthetic ionophores, in which more than single conformations are available owing to either crystalline polymorphs or a variety of metal‐ligand interactions. The magnitude of the conformation‐dependent 13 C chemical shifts are in many instances as large as 8 ppm and are well related to a set of torsion angles of nearby single bonds. The application of this concept to conformational characterization is also discussed.