Use of the pseudophase model in the interpretation of reactivity under restricted geometry conditions. An application to the study of the [Ru(NH(3))(5)pz](2+) + S(2)O(8)(2-) electron-transfer reaction in different microheterogeneous systems.

The title reaction has been studied under restricted geometry conditions, comprising aqueous solutions of a polymer (DNA), cyclodextrins, and dendrimers as well as (CTA)Cl micellar solutions and sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/water/oil microemulsions. The results are interpreted by taking as a general basis the pseudophase model, modified in some cases in order to take into account the specificity of the reaction medium. These modifications describe the anti-cooperative character of the binding of the substrates to the surfaces and the changes of the electric potential at the surfaces. The conclusion is that the pseudophase model is a powerful tool for the interpretation of kinetic data in the reaction media considered in this work, provided that the specificity of these media were incorporated into the model.