Our hypothesis is that well-defined, molecular cluster structures (MCSs) of DIPA and water form in DIPA-water mixtures. We test this hypothesis using x-ray total scattering, atomic pair distribution function (PDF) analysis and small-angle x-ray scattering (SAXS), together with molecular modeling and molecular dynamics (MD) simulations. Example MCSs are illustrated in Figure . The left-most MCS in Figure shows the basic building block, a DIPA-water dimer, where the oxygen of the water coordinates the nitrogen on the amine through a hydrogen bond. However, we are interested in searching for evidence for larger molecular clusters, as shown in Figure . For example, we show a dumbbell-shaped oligomer of two DIPA molecules with four molecules of water interposed (center). We also show a larger, reverse-micellar structure with multiple DIPAs organized around water in the center (right). In a liquid, should these structures be present, they will not be fully ordered, and indeed will be dynamically forming and breaking. However, if the structures have sufficiently-specific atom-atom coordinations, and persist for sufficient durations, they will yield a signal in the PDF. The experimentally-accessible PDF is a correlation function that measures the time average of the instantaneous relative positions of atoms in the liquid. An absence of features in this function implies an absence of structural correlations (specific structures), implying a high degree of randomness, and so high entropy. Conversely, the observation of correlations in the PDF signifies the opposite, i.e., order and thus, lower entropy.