  Water under nanoconfinement at ambient conditions has exhibited
low-dimensional ice formation and liquid-solid phase transitions, but with
structural and dynamical signatures which map onto known regions of waters
phase diagram. Using THz absorption spectroscopy and ab initio molecular
dynamics, we have investigated the ambient water confined in a supramolecular
tetrahedral assembly, and determined that a distinct network of 9-10 water
molecules is present within the nanocavity of the host. The low-frequency
absorption spectrum and theoretical analysis of the water in the
$Ga_4$$L_6$$^{-12}$ host demonstrate that the structure and dynamics of the
encapsulated droplet is distinct from any known phase of water. A further
inference is that the release of the highly unusual encapsulated water droplet
creates a strong thermodynamic driver for the high affinity binding of guests
in aqueous solution for the $Ga_4$$L_6$$^{-12}$ supramolecular construct.
