Electron transfer reactions, rate

Electron transfer reaction rates can depend strongly on tire polarity or dielectric properties of tire solvent. This is because (a) a polar solvent serves to stabilize botli tire initial and final states, tluis altering tire driving force of tire ET reaction, and (b) in a reaction coordinate system where the distance between reactants and products (DA and... 

Eig. 2. Electron-transfer reaction rate, vs exoergicity of reaction the dashed line is according to simple Marcus theory the soUd line and data poiats are... 

We are currently carrying out further investigations with neutral ferrocene derivatives in an attempt to resolve the apparent disconnection between the effects of CB7 encapsulation on homogenous and heterogeneous electron transfer reactions rates. 

Figure 4 Free energy dependence of electron transfer reaction rate for case A where —X is approximately equal to AGS (or AGp) and case B where —X is closer in energy to AGq.

The photoinduced electron transfer reaction rates depend strongly on the molecular structures of the donor and acceptor entities [16]. The nature of the linker between them influences the charge or energy transfer, which is facilitated considerably when both partners are connected by bridging ligands [13,17,31],... 

Usually, T is proportional to the viscosity, rj, of solvents. Therefore, the Kramers model predicts that the rate constant becomes proportional to in viscous solvents. Indeed, in solution reactions, including electron transfer reactions, rate constants are known to decrease with an increase in rj, as mentioned before. However, the observed dependence is not but... 

Other electron-transfer reaction rates which have been measured are those between phenothiazine cation-radical (249) and dimethyl- and tetra-methyl-p-phenylenediamines. Electron transfer takes place at the diffusion-controlled rate equilibrium constants were determined which demonstrated the greater stability of the Wurster s radicals over 249. This... 

For chronopotentiometry, the behavior of r is again like the Ci-Ej. case, since the wave will shift to sufficiently negative values to maintain the electron-transfer reaction rate at the value required by the applied constant current, and the treatment in Section 12.3.1 applies. 

The electron-transfer reaction rate for all these three cases can be presented as follows ... 

The recent determination of the crystallographic structure of a bacterial photosynthetic reaction center has provided an important framework for treating electron transfers in these systems. As in electron transfers in simpler systems, a knowledge of both the structure and the thermodynamics is needed for understanding the experimental results on reaction rates at the fundamental level. In this lecture we first describe the theory of simple electron transfer reaction rates, and then consider how the resulting interaction between theory and experiment may assist us in treating electron transfers in the photosynmetic reaction center. 

Huie RE, Clifton CL, Neta P (1991) Electron transfer reaction rates of the carbonate and sulfate radical anions. Radiat Phys Chem 38 477-481... 

So as to calculate electron transfer reaction rates in polar media,a number of effective approaches have been evolved based on model forms of the PES and on various models for evaluating the medium polarization and the energy of solvent reorganization [2,17,18,20,23-26]. Recently this analysis has been raised to the level of semiclassical trajectory calculations of the dynamics of above reactions [27]. At the same time, there are so far no sufficiently complete quantum mechanical calculations of the PES of the electron transfer reactions on account of complexities of the calculation involving extension of the basis sets and careful assessment of resolvation of the reactants in the development of the reaction process. 

S. Franzen, R. F. Goldstein, and S. G. Boxer, Electric field modulation of electron transfer reaction rates in isotropic systems long-distance charge recombination in photosynthetic reaction centers, J. Phys. Chem. 94 5135 (1990). 

---