Alkali cation-π aromatic conduction pathways in self-organized hybrid membranes

We report new hybrid organic-inorganic membrane materials in which alkali cations are envisioned to diffuse along cation-pi aromatic conduction pathways. The hierarchical generation of functional hybrid membrane materials has been realised in two steps. First, the self-assembling properties of 3-(ureidoarene)propyltriethoxysilane compounds in aprotic solvents were determined, revealing the formation of supramolecular oligomers. They led in a second sot-gel transcription step to self-organized hybrid membrane materials at nanoscopic scale. Finally they have been tested in dialysis transport experiments. The transport selectivity through self-organized membranes is due to the interaction of the partially hydrated ions with the hydrophilic or hydrophobic pathways within the matrix of the membrane. This interaction is governed by the energetic balance between the dehydration free energy and the binding energy of cation-pi interaction with the aromatic moieties. (C) 2008 Elsevier B.V. All rights reserved.