Synthesis, photophysical, and electrochemical properties of two polynuclear ruthenium(II) polypyridyl complexes containing diazafluorene

Abstract

Two polypodands, tetrakis[2-(4,5-diazafluoren-9-ylimino)phenoxymethyl]methane (L 1 ) and 1,1,1-tris[2-(4,5-diazafluoren-9-ylimino)phenoxymethyl]propane (L 2 ), and their corresponding Ru(II) polypyridyl complexes have been synthesized and characterized. The photophysical behaviors of the two complexes were investigated by UV-vis absorption and emission spectroscopy. They display metal-to-ligand charge transfer (MLCT) absorptions at around 443 nm in MeCN solution at room temperature and emission at around 573 nm in EtOH:MeOH (4:1) glassy matrix at 77 K. Electrochemical studies of the two complexes show one Ru(II)-centered oxidation at around 1.35 V and three ligand-centered reductions.

Coordination chemistry and applications of versatile 4,5-diazafluorene derivatives

“…9,10 A series of multinuclear Ru(II) complexes supported by multinucleating ligands possessing two or more chelating 4,5diazafluorenyl moieties have been explored. [122][123][124][125][126][127][128][129][130][131][132][133][134][135][136][137][138] The spacers between the coordinating 4,5-diazafluorenyl moieties have been varied substantially to allow for the metal-metal separation, and the degree of intramolecular charge transfer to be finely tuned. In some cases disappointingly the Ru(II) complexes had extremely short excited state lifetimes at room temperature on the order of ∼0.03 ns (e.g., Ru complex of the ditopic ligand with an adamantyl spacer).…”