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

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)2Ru(μ-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)2Ru(μ-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. Keywords: luminescence, ruthenium complexes, dendrimers, electrochemistry, photochemistry.