Preparation of Surfactant Ruthenium Complexes Containing 6,6′-BIS(N-Alkylbenzimidazolyl)-2,2′-Bipyridine with Long Alkyl Chains

New surfactant ruthenium complexes, [Ru(X)(Y)(L8 or 12)]n+, were synthesized by the reaction of [RuCl2(η6-p-cymene)]2 with L8 or 12 in methanol or DMSO, where L8 or 12 stands for tetradentate 6,6′-bis(N-octyl-or laurylbenzimidazolyl)-2,2′-bipyridine. The complexes formed stable monolayer films on the Langmuir trough at the air-water interface and were transferred to a glass plate. The π-A isotherms indicate the phase transition between expanded liquid state and the solid state at around 14 mNm−1, and monolayer collapses at a pressure of 45 mNm−1. This phase transition may be interpreted in terms of a change of molecular orientation. The structure of the LB films on glass were discussed.