  Hydroxide ion transport and structure in aqueous media is fundamental to many
chemical and biological processes. Research on hydroxide behavior has primarily
focused on a single fully solvated hydroxide, either as an isolated cluster or
in the bulk. This work presents the first computational study to consider a
medium of low hydration levels where the hydroxide ion is microsolvated. Under
such conditions, hydroxide ions are shown to be predominantly present as unique
water-bridged double-hydroxide charged clusters, distinct from previously
reported structures under hydrated conditions. Although layered double
hydroxides were reported in the crystalline state, this is the first time to be
seen in the disordered liquid state. These newly observed double-hydroxide
structures presumably disrupt the hydrogen bonded network required for
structural diffusion of hydroxide ions through water. These ion complexes have
a higher ionic strength which may explain the unexpected diffusion behavior in
comparison to the single hydroxide-water complex.
