Light-powered molecular shuttle

The strategy devised in order to obtain the photoinduced shuttling movement of R between the two stations Ai + and A2 + is based on a four stroke synchronized sequence of electron transfer and molecular rearrangement processes, as illustrated in Figure 27(b).Light excitation of the photoactive unit P + (process 1) is followed by the transfer of an electron from this unit to Ai + (process 2) which competes with the intrinsic decay of the P + excited state (process 3). After the reduction of Ai +, with the consequent deactivation of this station, the ring moves (process 4) by 1.3 nm to encircle A2 +, a step that is in competition with the back electron transfer from Ai+ (still encircled by R) to the oxidized unit P + (process 5). Eventually, a back electron transfer from the free reduced station Ai + to the oxidized unit P + (process 6) restores the electron-acceptor power to this radical cationic station. As... 

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