Rotational resonance NMR of C-13(2)-labelled retinal: quantitative internuclear distance determination

Rotational resonance phenomena are investigated in the solid-state magic-an gle spinning NMR of all-E-[11,20-C-13(2)]-retinal at a magnetic field of 4. 7 T. We find good agreement between experiments and numerical simulations f or the rotational resonance spectral peakshapes and for the rotor-driven ma gnetization exchange. The internuclear distance between the C-13-labelled C 11 and C20 sites is determined to be 0.301 +/- 0.008 nm (from rotational re sonance spectra) and 0.300 +/- 0.010 nm (from rotor-driven magnetization ex change), in agreement with the X-ray crystallographic distance of 0.296 nm. We show rotational resonance spectra which display perturbations from inte rmolecular homonuclear spin-spin interactions. (C) 1999 Elsevier Science B. V. All rights reserved.