Analytical Sciences

Electrochemical and Luminescent Properties of New Mononuclear Ruthenium(II) and Binuclear Iridium(III)-Ruthenium(II) Terpyridine Complexes

Naokazu YOSHIKAWA,* Takeko MATSUMURA-INOUE,** Nobuko KANEHISA,*** Yasushi KAI,*** Hiroshi TAKASHIMA,* and Keiichi TSUKAHARA*

*Department of Chemistry, Faculty of Science, Nara Women’s University, Nara 630-8506, Japan
**Minerva Light Laboratory, Seika-cho Hikaridai, Kyoto 619-0237, Japan
***Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Osaka 565-0871, Japan

Hexafluorophosphate salts of mononuclear complexes [Ru^IICl(L)(terpy)]⁺ (L = dmbpy (1); dpbpy (2), sambpy (3), and dpp (7), and binuclear complexes [Ru^II₂Cl₂(dpp)(terpy)₂]²⁺ (8) and [Ir^IIIRu^IICl₂(dpp)(terpy)₂]³⁺ (9) were prepared and characterized. Abbreviations of the ligands are bpy = 2,2′-bipyridine, dmbpy = 4,4′-dimetyl-2,2′-bipyridine, dpbpy = 4,4′-diphenyl-2,2′-bipyridine, dpp = 2,3-bis(2-pyridyl)pyrazine, sambpy = 4,4′-bis((S)-(+)-α-1-phenylethylamido)-2,2′-bipyridine, and terpy = 2,2′:6′,2″-terpyridine. The absorption spectra of 8 and 9 are dominated by ligand-centered bands in the UV region and by metal-to-ligand charge-transfer bands in the visible region. The details of their spectroscopic and electrochemical properties were investigated. In both binuclear complexes, it has been found that the HOMO is based on the Ru metal, and LUMO is dpp-based. [Ir^IIIRu^IICl₂(dpp)(terpy)₂]³⁺, indicating intense emission at room temperature, and a lifetime of 154 ns. The long lifetime of this bimetallic chromophore makes it a useful component in the design of supramolecular complexes.

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