Observation of Three Behaviors in Confined Liquid Water within a Nanopool Hosting Proton-Transfer Reactions

In this contribution, we report on studies of rotational and diffusional dynamics of 7-hydroxyquinoline (7HQ) within a reverse micelle (RM) containing different amounts of water. Analyzed in terms of the wobbling-in-a-cone model, the data reveal structural and dynamical properties of the nanopool. We clearly observed three regions in the behavior of confined water molecules within the RM hosting a double proton-transfer reaction between the probe and water. This observation remarkably reproduces the change of calculated water density within this life-mimicking medium. The number of water molecules per AOT head in the transition regions changes from 2 to 5, the latter being very near to the full solvation number (6) of the RM heads. Moreover, the H-bonds breaking and making within the RM to give new structures of the probe strongly affect the environment fluidization in different extents, reflected in different relaxation times of these structures; however, they are of similar sizes. We discuss the role of RM confinement and the proton-transfer dynamics on the behavior of water and their relationships to the packing of water molecules in the studied range of concentrations.