  We present an unprecedented fluoride-water cyclic cluster of
$[F(H_2O)]_4^{4-}$ assembled in a cuboid-shaped molecular box formed by two
large macrocycles. Structural characterization reveals that the
$[F(H_2O)]_4^{4-}$ is assembled by strong H-bonding interactions (OH...F =
2.684(3) to 2.724(3) {\AA}), where a fluoride anion plays the topological role
of a water molecule in the classical cyclic water octamer. The interaction of
fluoride was further confirmed by $^{19}$F NMR and $^1$H NMR spectroscopies,
indicating the encapsulation of the anionic species within the cavity in
solution. High level DFT calculations and Bader topological analyses fully
support the crystallographic results, demonstrating that the bonding
arrangement in the fluoride-water cluster arises from the unique geometry of
the host.
