Photoinduced electron exchange

This may not be the full answer as the photoinduced electron exchange between pyrene, P, and dimethylaniline, D, on CTAB micelles and other CTAB structures, etc.,... 

Sekiguchi S, Kobori Y, Akiyama K and Tero-Kubota S 1998 Marcus free energy dependence of the sign of exchange interactions in radical ion pairs generated by photoinduced electron transfer reactions J. Am. Chem. Soc. 120 1325-6... 

Photoinduced Sj l aromatic substitutions apparently involve primary photochemical electron transfer. Hoz and Bunnett, for example, have characterized the mechanistic details of photoinitiation in the reaction of iodobenzene with diethyl phosphite as involving either electron exchange, eq. 61 (188),... 

The requirement for AlCh adds some obvious limitations, but a modest number of substituted arenes have been successfully coordinated to the [FeCp]+ unit. Photoinduced arene exchange has been described43 and is particularly effective with the -r -chlorobenzene-r -cyclopentadienyliron cation without the need for Lewis acids.42 More basic (electron rich) arenes readily replace chlorobenzene, leading to FeCp cation complexes of O-phenylethyl-p-toluenesulfonate and variously substituted thiophenes.42 The charged complexes are not purified by conventional organic techniques, such as chromatography, but re-crystallization is possible. The complexes are very air and heat stable again, methods of removal of the arene from the Fe are few. The simplest is pyrolysis at >200 C.46... 

We have already seen that photoactive clusters, e.g. CdS, can be introduced into vesicles and BLMs (Sect. 5.2 and 5.3). Similar support interactions are possible with both inorganic and organic polymeric supports. Photoactive colloidal semiconductor clusters can be introduced, for example, into cellulose [164], porous Vycor [165], zeolites [166], or ion exchange resins [167]. The polymer matrix can thus influence the efficiencies of photoinduced electron transfer by controlling access to the included photocatalyst or by limiting the size of the catalytic particle in parallel to the effects observed in polymerized vesicles. As in bilayer systems,... 

Figure 2.14 Schematic representations of the mechanisms of photoinduced (a) electron transfer, (b) Dexter (electron-exchange) energy transfer, and (c) Fdrster (dipole-dipole) energy transfer mechanism processes in the supramolecular dyad A-L-B spheres represent electrons, while curved arrows indicate the directions of transfer...

To perform a highly stereoselective photoinduced electron transfer reaction, we need an optically pure photosensitizer and a substrate that do not cause photo-induced racemization. In addition, we need the substrate of which the self-exchange reaction occurs slowly or does not occur. If not, the stereoselectivity disappears, as was mentioned above. 

We thank P. Freeman for helpful discussions of photoinduced electron transfer from amines to halocarbons. We thank R. Wever and A. Butler for useful information and exchanges related to haloperoxidase-catalyzed reactions. We thank J. Hoigne and J. Leenheer for providing samples of NOM isolated from the Greifensee in Switzerland and from the Suwannee River in southern Georgia. 

Photoinduced Electron-Transfer Reactions 13.4.2. Excited-State Electron Exchange... 

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