Detection of hydrophobic microdomains in anionic polyelectrolytes with tris-(4,7-diphenyl-1,10-phenanthroline)3Cr(III).

This paper describes the changes in the luminescent properties of the tris-(4,7-diphenyl-1,10-phenanthroline)(3)Cr(III), [Cr(dip)(3)](3+) complex in an aqueous solution of three polyelectrolytes containing cyclohexyl, phenyl or 1-naphthyl groups in the side chain. When the polyelectrolytes form hydrophobic microdomains the luminescence of [Cr(dip)(3)](3+) is affected. The luminescence increases in the presence of cyclohexyl groups in the side chains, but decreases in the presence of phenyl and naphthyl groups (in that order).

Tuning the electronic communication and rates of intramolecular electron transfer of dimers of trinuclear ruthenium clusters: bridging and ancillary ligand effects.

Ten new bridged dimers of oxo-centered triruthenium clusters with CO and 4-(dimethylamino)pyridine (dmap), pyridine (py), or 4-cyanopyridine (cpy) as terminal ligands and pyrazine-d(4) (d(4)-pz), 2,5-dimethylpyrazine (dmpz), 2-methylpyrazine (mpz), and 2-chloropyrazine (clpz) as bridging ligands were prepared. The carbonyl stretching frequency, nu(CO), was used as a probe for infrared spectroelectrochemical measurements. In the neutral and doubly reduced states, a single band was observed for each of the dimers, with a shift in frequency due to the oxidation state of the triruthenium clusters.

Infrared activity of symmetric bridging ligand modes in pyrazine-bridged hexaruthenium mixed-valence clusters.

A fully symmetric (A(g)) vibrational mode of pyrazine is observed in the infrared spectrum of four pyrazine-bridged hexaruthenium mixed-valence complexes with varying degrees of electronic coupling between clusters. Deuteration of the bridging pyrazine ligand and the accompanying shift in frequency confirm the assignment of this mode. Previous observation of infrared line coalescence in the carbonyl stretching region assigns all of these complexes to Robin-Day class II (partial localization of charge) on the picosecond time scale.

Solvent dynamical control of electron-transfer rates in mixed-valence complexes observed by infrared spectral line shape coalescence.

Rate constants for intramolecular electron transfer within the intervalence charge transfer (-1) states of the complexes [{Ru3O(OAc)6(L)(CO)}2(mu-pz)] (where L= 4-(dimethylamino)pyridine (1), pyridine (2), 3-cyanopyridine (3), or 4-cyanopyridine (4) and pz = pyrazine) were determined by coalescence of infrared (IR) vibrational spectral line shapes in seven solvents. The electron-transfer times (kET-1) show a strong correlation with solvent relaxation times determined in separate ultrafast time-resolved fluorescence experiments. The best comparison is found with the parameter t1e, which is ascribed to inertial solvent relaxation.