The Influence of Electrical Polarization

Such a mechanism appears to be adequate enough for the description of the carrier-mediated electron transfer across membranes. It allows, for example, one to describe quantitatively the influence of electrical polarization on the transmembrane electron transfer. 

The influence of electrical polarization of the membrane on electron transfer provided by dihexadecylviologen radical cation was studied in Refs. [77, 201]. These studies were made in order to verify the assumption that the electric field, arising in the membrane during reaction (36), decelerates further electron transfer. C16V0+ut radical cations were generated only in the outer monolayer of the membrane by means of flash photolysis of the vesicle suspension containing 

Fe(CN). ..in the inner cavities. If, at the initial moment of time, on average less 

Note that after eight C16V+ particles are transferred across the membrane, the deviations of the reaction kinetics from the first-order law again disappear. This apparently corresponds to the above mentioned case when the rate of C16V+ transfer becomes controlled by the rate of charge neutralization (see Sect 4.1.1). The rate constant of the transfer here amounts 0.64 s 1, and is close to that (0.4 s-1) measured for reaction (36) by the stopped-flow method. 

Bienvenue et al. [96] used the expression similar to Eq. (40) to describe quantitatively the dependence of the photocurrent through the planar BLM upon the applied photo voltage AU in the System 40 of Table 1. Photocurrent was caused by the the transfer through membrane of ZnTPP+ radical cations. Note that in this case the potential difference affecting the motion of ZnTPP+ cation is equal to only 60% of the external voltage apparently due to the location of ZnTPP+ sufficiently deep below the surface of the membrane. 

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