Observation of three behaviors in confined liquid water within a nanopool hosting proton-transfer reactions

J Phys Chem B. 2007 May 17;111(19):5487-93. doi: 10.1021/jp068764+. Epub 2007 Apr 24.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Hydrogen-Ion Concentration
  • Hydroxyquinolines / chemistry*
  • Models, Molecular
  • Molecular Structure
  • Nanostructures / chemistry*
  • Protons
  • Time Factors
  • Water / chemistry*

Substances

  • Hydroxyquinolines
  • Protons
  • Water