Properties Of Ruthenium Polypyridyl Complexes Research Articles

Improving the Photosensitizing Properties of Ruthenium Polypyridyl Complexes Using 4-Methyl-2,2′-bipyridine-4′-carbonitrile as an Auxiliary Ligand

We report in this work the synthesis and spectroscopic, electrochemical, spectroelectrochemical, and photophysical characterization of a novel series of ruthenium polypyridyl complexes with 4-methyl-2,2'-bipyridine-4'-carbonitrile (Mebpy-CN) as an auxiliary ligand of general formula [Ru(bpy)3-x(Mebpy-CN)x](PF6)2 (x = 1-3) (with bpy = 2,2'-bipyridine). A significant increase in the lifetime and quantum yield of emission of the lowest (3)MLCT excited state is disclosed when going from x = 1 to x = 3, evidencing an improvement of the photosensitizing properties with respect to [Ru(bpy)3](PF6)2. Furthermore, quenching by molecular oxygen of (3)MLCT excited states of the three complexes produced singlet molecular oxygen ((1)O2) with quantum yield values higher than that of [Ru(bpy)3](2+) in CH3CN. The structure of the complex with x = 1 has been determined by X-ray diffraction. The photoconductivity of ZnO nanowires covered with this same complex is increased by an order of magnitude, pointing to its feasibility as a component of a DSSC. A new dinuclear complex with Mebpy-CN as a bridging ligand has also been prepared and characterized by physicochemical techniques. The derived mixed-valent species of formula [(bpy)2Ru(II)(Mebpy-CN)Ru(III)(NH3)5](5+) displays a considerable metal-metal electronic coupling due to the delocalization effect of a nitrile group in the 4' position of the bpy ring.

ChemInform Abstract: Excited-State Properties of Ruthenium(II) Polypyridyl Complexes Containing Asymmetric Triazole Ligands

Abstract The photochemical and photophysical properties of ruthenium polypyridyl complexes containing 1,24-triazole-based ligands, such as pyridine- and pyrazine triazoles are reviewed. The excited-state behaviour of such complexes is discussed in relation to the asymmetry inherently present in these ligands. For the pyridine triazole-containing complexes a series of photochemically induced isomerisations is reported. Pyrazine triazole compounds show a very unusual dual emission, which has been investigated using temperature dependent emission lifetime studies and partial deuteriation.

The photophysical properties of ruthenium polypyridyl complexes within a sol-gel matrix

The photophysical properties of ruthenium polypyridyl complexes within a sol-gel matrix

The Photophysical Properties of Ruthenium Polypyridyl Complexes within a Sol-Gel Matrix

Tetraethoxysilane (TEOS) sol-gel monoliths impregnated with three different luminescent [Ru(L)3]2+ complexes (where L = 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), or 4,7-diphenyl,1,10-phenanthroline (dpp)) have been prepared. The photoluminescence properties of these complexes were followed as a function of time, as the sol-gel reactions proceeded. Clear differences were observed in the emission energies and the emission lifetimes of the complexes upon gel formation. These differences can be explained by the different extent of electrostatic interaction between the surface of the siloxane polymer and the immobilised complex.

The pH dependence of the emitting properties of ruthenium polypyridyl complexes bound to poly-l-lysine

The synthetic poly-amino acid, poly-l-lysine has been covalently coupled to a ruthenium polypyridyl complex, a long-lived fluorescent species, via a thiourea linkage between the amino side groups of the lysine residues and the isothiocyanate group of the label. The pH dependence of the emission lifetime of the label is reported whereby the behavior observed is explained in terms of the conformational changes of the bound biomolecules due to the label's sensitivity to its local environment.