Combination of radical ions

A special case of donor-acceptor interactions occurs when two monomers come into contact such that one exhibits a signicant donor and the other an acceptor character. The donor-acceptor complex then has the structure of a zwitterion resulting from the combination of radical ions after electron transfer from donor to acceptor... 

All these processes are retrodimerizations. The characteristic of the corresponding cycloadditions is that the sensitizer, while being essential for activating the reactants (by photoinduced electron transfer) and for making the products persist (by back electron transfer), takes no part in the cycloaddition proper, the key step of which is the combination of a radical ion with its parent molecule. For cycloadditions of unlike species, another mechanistic pathway is open, namely, via direct combination of radical ion pairs, as was reported in several recent publications [117],... 

According to the first approach, an interaction of the electron-donating (styrene) and the electron-accepting (MAH) monomers results in a charge transfer complex. It is a combination of radical ions formed by electron transfer from styrene to MAH. MAH, included into CTC, shows an increased reactivity toward macroradicals. 

E and enol radical cations, E. After this occurs, however, it is not clear whether K forms simply through tautomerization of E, or by combination of radical ions of the keto form which may arise from tautomerization of enol radical ions, of which many pathways can be supposed. The detailed mechanism of the observed EGIPT luminescence remains to be established. 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

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