  Water is the liquid of life, thanks to its three-dimensional adaptive
hydrogen (H)-bond network. Confinement of this network may lead to dramatic
structural changes that influence chemical and physical transformations.
Although confinement effects occur on a < 1 nm length scale, the upper length
scale limit is not known. Here, we investigate 3D confinement over lengths
scales ranging from 58 - 140 nm. By confining water in zwitterionic liposomes
of different sizes and measuring the change in H-bond network conformation
using second harmonic scattering (SHS) we determined long range confinement
effects in light and heavy water. D2O displays no detectable 3D-confinement
effects < 58 nm (< 3.10^6 D2O molecules). H2O is distinctly different: The
vesicle enclosed inner H-bond network has a different conformation compared to
the outside network and the SHS response scales with the volume of the
confining space. H2O displays confinement effects over distances > 140 nm (>
4.10^7 H2O molecules).
