1,10-Phenanthroline and 1,10-phenanthroline-terminated ruthenium(II) complex as efficient capping agents to stabilize gold nanoparticles: application for reversible aqueous-organic phase transfer processes.

1,10-Phenanthroline (phen) and 1,10-phenanthroline-terminated ruthenium(II) complex [Ru-Lphen](2+) have been used to stabilize and functionalize gold nanoparticles (Au-NPs). The strong interaction between the nitrogen atoms of phen and the surface of Au-NPs allowed for the phase transfer of Au-NPs from toluene to aqueous phase containing [Ru-Lphen](2+). Reverse phase transfer of these Au-NPs from water to acetonitrile by substituting the Cl(-) counter anion by PF(-)(6) has also been demonstrated. Such facile post-functionalization, phase transfer and solvent transfer processes using metallic complexes bearing a terminal phenanthroline pendant group constitute a prerequisite for further studies of the electronic and optical properties of these NCs in various media.