The interactions of macrocyclic ethers by 13C dipole-dipole relaxation time measurements

¹³C dipole–dipole relaxation time measurement studies of free and cation complexed cyclic polyethers in solution are reviewed briefly. The ¹³C dipole–dipole relaxation time of the macrocyclic ether backbone has been recognized to be a function of a motion of the molecular segment acting as a macrocyclic ligand site. This has been particularly investigated by NMR under extreme narrowing conditions.