  We have performed a thorough examination of the reorientational relaxation
dynamics and the ionic charge transport of three typical deep eutectic
solvents, ethaline, glyceline and reline by broadband dielectric spectroscopy.
Our experiments cover a broad temperature range from the low-viscosity liquid
down to the deeply supercooled state, allowing to investigate the significant
influence of glassy freezing on the ionic charge transport in these systems. In
addition, we provide evidence for a close coupling of the ionic conductivity in
these materials to reorientational dipolar motions which should be considered
when searching for deep eutectic solvents optimized for electrochemical
applications.
