Conformational features of charged dibucaine in solution as investigated by 13C- and 1H-NMR

Conformational features of charged dibucaine in [2H6]DMSO were elucidated by measuring 13C and 1H spin-lattice relaxation rates and 1H-(1H) and 13C-(1H) nuclear Overhauser effects. The reorientational correlation time of the aromatic moiety was evaluated at 0.16 ns at room temperature and side chains were observed to display segmental motion. Relevant distances were calculated by isolating dipolar interaction terms of 1H-1H or 13C-1H pairs. The 'preferred' conformation in solution was shown to present several analogies, but also some differences, with the structures obtained by solid state experiments, energy calculations and LIS data.