  The temperature dependence of the structure of water confined in hydrophilic
mesostructured porous silica (MCM-41) and hydrophobic benzene-bridged periodic
mesoporous organosilicas (PMO) is studied by Raman vibrational spectroscopy.
For capillary filled pores (75% relative humidity, RH), the OH-stretching
region is dominated by the contribution from liquid water situated in the core
part of the pore. It adopts a bulk-like structure that is modestly disrupted by
confinement and surface hydrophobicity. For partially filled pores (33% RH),
the structure of the non-freezable adsorbed film radically differs from that
found in capillary filled pores. A first remarkable feature is the absence of
the Raman spectral fingerprint of low density amorphous ice, even at low
temperature (-120{\textdegree}C). Secondly, additional bands reveal water
hydroxyls groups pointing towards the different water/solid and water/vapor
interfaces. For MCM-41, they correspond to water molecules acting as weak
H-bond donors with silica, and dangling hydroxyl groups oriented towards the
empty center of the pore. For benzene-bridged PMO, we found an additional type
of dangling hydroxyl groups, which we attribute to water at hydrophobic solid
interface.
