Electron Transfer Reactions in Micellar Systems

The influence of micelles on electron transfer processes is reviewed. The micelles modify the rate of electron transfer reactions by producing changes in all the relevant parameters controlling this rate; that is, through modification of the reorganization free energy, the reaction free energy, the nuclear dynamics and the strength of the coupling between the donor and the acceptor. Applications of studies on electron transfer reactions in micellar systems in different fields are presented.

On the Equivalence of the Pseudophase Related Models and the Brönsted Approach in the Interpretation of Reactivity under Restricted Geometry Conditions

The equivalence of the Pseudophase and related models, frequently used in the interpretation of kinetic data under restricted geometry conditions, and the well known Brönsted's equation, used in the interpretation of the reactivity in homogeneous media, has been proven in several cases. The generalisation in relation to other non-kinetic properties such as reaction free energy and redox potentials has also been considered.

Method for the Evaluation of the Reorganization Energy of Electron Transfer Reactions Produced under Restricted Geometry Conditions

The kinetics of the electron transfer reactions between S(2)O(8)(2-) and the complexes (Ru(NH(3))(5)L)(2+) (L = pyridine, pyrazine, and 4-cyanopyridine) have been studied in micellar (SDS) solutions. A method for the evaluation of the reorganization energy of these reactions, based on the comparison of their rate constants, is proposed. From the results obtained, we concluded that the observed rate constants go through a minimum for the surfactant concentration in which the reorganization energy goes through a maximum. The method can be applied to any kind of restricted geometry conditions.

Estimation of Electron Transfer Rate Constant from Static (Optical and Thermodynamic) Measurements: A Study of Ru(NH(3))(5)pz(2+) + Fe(CN)(6)(3)(-) right harpoon over left harpoon Ru(NH(3))(5)pz(3+) + Fe(CN)(6)(4)(-) Electron Transfer Reactions

A kinetic study of the electron-transfer reactions Ru(NH(3))(5)pz(2+) + Fe(CN)(6)(3-) right harpoon over left harpoon Ru(NH(3))(5)pz(3+) + Fe(CN)(6)(4-) was carried out in several water-organic solvent mixtures at 298.2 K. The free energies of activation for these thermal electron-transfer reactions were calculated from a combination of spectroscopic and thermodynamic data and are compared with those obtained from the kinetic study. Quantitative agreement is found between the two series of data. This shows the possibility of estimating activation free energies for electron-transfer reactions from these (static) measurements.