Protected building blocks for luminescent and redox-active dendritic metal complexes. Excited state properties and electrochemical behavior

The mononuclear complexes [Ru(2,3-Medpp)(3)](5+), [Ru(2,3-Medpp)(2)(bpy)](4+), and [Ru(2,3-Medpp)(bpy)(2)](3+) and the dinuclear complex [(2,3-Medpp)(2)Ru(mu-2,3-dpp)Ru(2,3-Medpp)(2)](8+) (bpy = 2,2'-bipyridine; 2,3-dpp = 2,3-bis(2-pyridyl)pyrazine; 2,3-Medpp(+) = monomethylated 2,3-bis(2-pyridyl)pyrazine) have been synthesized. Their absorption spectra, luminescence properties, and electrochemical behavior have been investigated and compared with those of the mononuclear [Ru(bpy)(3)](2+), [Ru(2,3-dpp)(3)](2+), [Ru(2,3-dpp)(2)(bpy)](2+), and [Ru(2,3-dpp)(bpy)(2)](2+) and the dinuclear [(bpy)(2)Ru(mu-2,3-dpp)Ru(bpy)(2)](4+) parent compounds. The complexes examined are fundamental units in the synthesis of polynuclear metal complexes of dendrimeric structure and nanometer size.