  We demonstrate, by means of Grand Canonical Monte Carlo simulation on
different members of the ZIF family, how topology, geometry, and linker
functionalization drastically affect the water adsorption properties of these
materials, tweaking the ZIF materials from hydrophobic to hydrophilic. We show
that adequate functionalization of the linkers allows one to tune the
host-guest interactions, even featuring dual amphiphilic materials whose pore
space features both hydrophobic and hydrophilic regions. Starting from an
initially hydrophobic material (ZIF-8), various degrees of hydrophilicity could
be obtained, with a gradual evolution from a type V adsorption isotherm in the
liquid phase to a type I isotherm in the gas phase. This behavior is similar to
what was described earlier in families of hydrophobic all-silica zeolites, with
hydrophilic "defects" of various strength, such as silanol nests or the
presence of extra-framework cations.
