Manipulation of the nuclear overhauser effect by the use of a viscous solvent: the solution conformation of the antibiotic echinomycin

Abstract
In an experiment which should be of wide applicability, a viscous solvent has been used to induce relatively slow tumbling of the solute; under these conditions, negative n.O.e.'s may be observed and, in the present case, these have been used to deduce the solution conformation of echinomycin.