A novel binuclear ruthenium complex: Spectroscopic and electrochemical characterization, and formation of Langmuir and Langmuir-Blodgett films

[{RuCl3(dppb)}(2)(mu-4,4'-bipy)] was prepared from the reaction of the 4,4'-bipyridine and mer-[RuCl3(dppb)]center dot H2O, in good yield. The characteristics of the binuclear complex studied with FT-IR, UV-Vis, EPR and elemental analysis were similar to those of the [RuCl3(dppb)L] (L= N-heterocycle). [{RuCl3(dppb)}(2)(mu-4,4'-bipy)] is soluble in weakly polar organic solvents, facilitating its use in the production of Langmuir and Langmuir-Blodgett (LB) films production. While the cast films and the complex in solution were red, the LB films were green-bluish, probably due to oxidation of the bisphosphine. The nanostructured nature of the LB films was manifested in electrochemical measurements, as these films exhibited higher peak currents than cast or dipcoated films. For all films, the electrochemical response was dominated by the (RuRuIII)-Ru-III/(RuRuII)-Ru-II process, which differed from that of the binuclear compound. For the latter, an irreversible process appeared due to formation of new species. The electroactivity of LB films from [{RuCl3(dppb)}(2)(mu-4,4'-bipy)] also pointed to their possible use in electrochemical devices.