Selective internuclear coupling estimation in the solid-state NMR of multiple-spin systems

Abstract

A new solid-state NMR method is presented for estimating homonuclear dipole–dipole couplings for selected groups of nuclear spins in a multiple-spin coupled network. The methodology combines off-magic-angle spinning, frequency selective spin echoes, and multiple quantum filtering. The new method is insensitive to incoherent relaxation effects and may be used to estimate weak couplings. Internuclear ¹³C–¹³C couplings are estimated in uniformly ¹³C-labelled L-Histidine·HCl·H₂O. Weak intermolecular couplings between ¹³C nuclei separated by distances exceeding 6 Å are estimated.