ELECTRON LOCALIZATION AND DELOCALIZATION IN BISELECTROPHORES

We have performed ESR and pulsed ENDOR experiments on the radical anions of [2.2]-(9,10)-anthracenophane (1), 1,2-di(9-anthryl)ethane (2a), 1,3-di(9-anthryl)propane (2b), 1,2-di-(2-anthryl)ethane (3), and the doubly layered [14]-annulene (4), both in the liquid and solid state. In the molecules 1,2 and 4 we have observed that the electron is delocalized over both subunits in the liquid state, whereas it is localized on one aromatic unit in the solid state. The transition from the delocalized to the localized state is observed to occur right at the liquid-to-solid phase transition temperature. For 1,2-di-(2-anthryl)ethane we always observe a localized spin both in the liquid and in the frozen solution.