Measurement of Internuclear Distances by Switched Angle Spinning NMR

Chem. Phys. 1986,85, 38161, has been used to measure I3C-l3C distances in the solid state. The experiment involves rotation of the sample at two different angles during different periods of a two-dimensional experiment. An evolution period with off-magic-angle spinning and chemical shift refocusing, followed by detection of the signal under magic angle spinning, yields scaled Pake patterns in 01, correlated with their isotropic shifts in 02, allowing the highrresolution measurement of dipolar couplings. We demonstrate this experiment on samples of doubly I3C labeled zinc acetate and a 14 amino acid peptide, in which we show that under optimal conditions distances of up to 5 A may be measured