Solvational change between initial

The theoretical treatment of liquid-phase reaction kinetics is limited by the fact that no single universal theory on the liquid state exists at present. Problems which have yet to be sufiiciently explained are the precise character of interaction forces and energy transfer between reacting molecules, the changes in reactivity as a result of these interactions, and finally the role of the actual solvent structure. Despite some hmitations, the absolute reaction rates theory is at present the only sufficiently developed theory for processing the kinetic patterns of chemical reactions in solution [2-5, 7, 8, 11, 24, 463-466]. According to this theory, the relative stabilization by solvation of the initial reactants and the activated complex must be considered cf. Section 5.1). 

The multiparameter equation (7-54) seems to be rather difficult to apply. However, in practice, most of the linear solvation energy relationships that have been reported are simpler than indicated by Eq. (7-54) since one or more terms are inappropriate. For example, if the solute property A does not involve the creation of a cavity or a change in cavity volume between initial and activated or excited states (as is the case for solvent effects on spectral properties), the term is dropped from Eq. (7-54). If the solvent-dependent process under study has been carried out in non-HBD solvents only, the a term drops out. On the other hand, if the solutes are not hydrogen-bond donors or Lewis acids, the P term drops out of Eq. (7-54). Thus, for many solvent-dependent processes, Eq. (7-54) can be reduced to a more manageable one-, two- or three-parameter correlation equation by a judicious choice of solutes and solvents [226],... 

All the ion and solvation changes discussed so far in this section relate to chemically reversible processes. Anecdotally, it is widely accepted in the redox polymer modified electrode literature that the first redox cycle of a newly deposited film is atypical. Although the reasons and processes are chemically rather different, this is reminiscent of the first cycle effect discussed in Sect. 2.7.3.6 for Prussian Blue films. PVF provides a typical example of this first cycle, or break-in , effect. The initial EQCM response to PVF oxidation in water (after its deposition from an organic solvent, typically dichloromethane) is quite different from that of a previously cycled film [132]. The result is most clearly demonstrated by considering the mass flux - or, better stiU, the difference between the total mass flux and the elec-tron/ion flux-as a function of apphed potential or film charge. Such plots show a once-only pulse of solvent into a new film this solvent (typically ca. five solvent molecules per ferrocene redox site) is retained ( trapped ) within the film thereafter and provides the baseline upon which subsequent redox-driven solvation... 

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