Metal coordination to amphiphilic Ru complexes at the air-water interface

We have examined the applicability of metal complex as a ligand' strategy at the interface by using the Ru complexes acting as a ligand. New amphiphilic ruthenium complexes containing 2,6-bis(1-octadecylbenzimidazolyl)-pyridine (L18), [Ru(L18)(X)](2+) were synthesized, where X = 2,3,5,6-tetrakis(2'-pyridyl)pyrazine (tppz) and 1,4-bis(2,2':6',2 "-terpyridine-4'-yl)benzene (bteb), in which the bis-tridentate ligand (tppz or bteb) of [Ru(L18)(X)](2+) can act not only as a hydrophilic head group but also as a coordination site to a metal ion from the subphase at the air-water interface. These amphiphilic Ru complexes lead to a stable Langmuir-Blodgett (LB) film formation. The incorporation of metal ion from subphase at the air-water interface was proved by the measurements of pi-A isotherms, UV spectra and angular dependent XPS spectra. (C) 1998 Published by Elsevier Science Limited. All rights reserved.