Salt and Solvent Effects on the Kinetics of the Oxidation of the Excited State of the [Ru(bpy)₃]²⁺ Complex by S₂O₈^2-

Abstract

The title reaction was studied in different reaction media: aqueous salt solutions (NaNO3) and water-cosolvent (methanol) mixtures. The observed rate constants, k(obs), show normal behavior in the solutions containing the electrolyte, that is, a negative salt effect. However, the solvent effect is abnormal, because a decrease of the rate constant is observed when the dielectric constant of the reaction medium decreases. These effects (the normal and the abnormal) can be explained using the Marcus-Hush treatment for electron transfer reactions. To apply this treatment, the true, unimolecular, electron-transfer rate constants, k(et), have been obtained from k(obs) after calculation of the rate constants corresponding to the formation of the encounter complex from the separate reactants, k(D), and the dissociation of this complex, k(-D). This calculation has been carried out using an exponential mean spherical approach (EMSA).

Design and development of photoanodes for water-splitting dye-sensitized photoelectrochemical cells

“…206 If the persulfate ion is in excess at concentrations on the order of millimolar or higher, the reaction between [Ru(bpy) 3 ] 2+ * and persulfate is essentially diffusion controlled, with nearly all [Ru(bpy) 3 ] 2+ * oxidized as in eqn (3). At lower persulfate concentration, some excited sensitizer molecules decay via eqn (2).…”

Electrochemiluminescence of the [Ru(bpy)3]2+ Complex: The Coreactant Effect of PAMAM Dendrimers in an Aqueous Medium

“…24 However, in the presence of dendrimer solutions at 1.0 × 10 −4 mol dm −3 of the ruthenium(II) complex, the cathodic currents were small, and for practical reasons, the DPV technique was used for evaluating E°′. Figure 3 shows a typical differential pulse voltammogram.…”

Tailoring mixed-valence CoIII/FeII complexes for their potential use as sensitizers in dye sensitized solar cells

“…The shifts of the MLCT/MMCT band maximum to lower energies compared to the values in water solution agrees fairly well with the weak nature of the inter-action of the complex with the oxide surface (acting as a solvent). 10,43 In fact the value obtained for the spectrum in MeCN solution is indicative of the shift expected for a practically non-interacting solvent. 44 As for the reduction potential of the iron centre in the attached samples Fig.…”