Conformational changes and electron transfer

Strong conformational changes may accompany electron transfer. This issue has been discussed in Section 1.5 and illustrated by an experimental example in Section 1.5.5, in the case where conformational change and electron transfer are concerted and the second electron transfer becomes easier than the first. Conformational changes do not necessarily cause the second electron transfer to be easier than the first. In all cases, their influence on the kinetics and mechanisms of electrochemical reactions should be analyzed. 

When conformational change and electron transfer are concerted, the structural change may be treated as an internal reorganization factor in the electron transfer dynamics. This is the A, term of the Marcus-Hush model (Section 1.4.2 see also Section 1.4.4 for experimental examples). The model is applicable as long as the conformational changes are not so strong as to invalidate the harmonic approximation. 

Dorfman et al have used theoretical models to examine the probabilities of photoinduced charge separation in solid matrices which are relatively concentrated in acceptors ([donor) [acceptor]). " Hoffman et al have presented a readable discussion of the coupling between slow nuclear motions of environmental species, such as might be the case for some conformational changes, and electron transfer processes.Such coupling has been labeled gated electron transfer. Simon and Su have used the fluorescence Stokes shift, band shape, and decay kinetics of 6w-(dimethylaminophenyl)-sulfone, which has a twisted intramolecular charge transfer excited state, to examine... 

---