DETERMINATION OF C-N INTERNUCLEAR DISTANCES BY ROTATIONAL-ECHO DOUBLE-RESONANCE NMR OF SOLIDS

Rotational-echo, double-resonance (REDOR) 15N13C NMR has been performed on an alanine cocrystallized from five-component alanines, isotopically enriched in 13C, 15N, or 12C. REDOR 15N13C NMR involves the dephasing of carbon magnetization by 15N 180° pulses synchronized with magic-angle spinning. The CN dipolar coupling determines the extent of dephasing. The results of these experiments on alanine show that it is practical to use REDOR to measure the CN dipolar coupling of 5 μmol of a 13C15N-labeled pair having an Internuclear separation of the order of 4.5 Å. © 1990.