Photoinduced electron transfer between quinones and amines in micellar media: Tuning the Marcus inversion region

Electron transfer (ET) rates between quinone acceptors and amine donors in micellar media show Marcus inversion behavior on correlating with the free energy changes of the ET reactions. The onset of Marcus inversion in these systems is seen to be tuned by about 0.25 eV by changing the type of the micelle. The results are rationalized on the basis of two-dimensional ET theory where ET occurs along intramolecular coordinate with non-equilibrium configuration along solvation coordinate. Maximum ET rates are seen to vary by about one order of magnitude in different micelles. and are attributed to the micelle-dependent changes in the separations of the interacting quinone-amine pairs. Tunings of Marcus inversion and ET rates by changing micellar microenvironments have been observed and suggested to have useful implications in different applied areas. (C) 2008 Elsevier B.V. All rights reserved.