Molecular dynamics of hydantoins and barbiturates assessed by 1H, 13C and 15N relaxation data

Abstract

The molecular dynamics of hydantoin, 5,5-dimethylhydantoin, 5,5-diphenylhydantoin, barbituric acid and 5-ethyl-5-phenylbarbituric acid in solution are determined to investigate the molecular basis for the activity of these neuroactive drugs. From dipolar 13C and 15N spin-lattice relaxation times the correlation times for the rotational dynamics of specific bond vectors are evaluated. Conclusions can be drawn concerning the anisotropy of the overall molecular rotational motion and the internal rotations of molecular segments. The translational molecular diffusion coefficients are obtained from self-diffusion measurements by the pulsed gradients method. The observed differences in the dynamics as well as structural differences may account for the variation in the neuroactivity of the studied compounds.