Water is an integral and functional component for aqueous assemblies of POSS-NDI-POSS molecules. Water serves not only as a solvent but also as an integral component (interstitial water) in aqueous colloids self-assembled from POSS-NDI-POSS (POSS = polyhedral oligomeric silsesquioxanes, NDI = naphthalene diimide). The interstitial water confined within these colloids is attributed to the steric hindrance of the bulky POSS groups, which dissipates energy and quenches the fluorescence (FL). Control experiments with NDI molecules bearing less steric side groups (propyl or octyl), namely C