Dual absorption spectral changes by light-triggered shuttling in bistable [2]rotaxanes with non-destructive readout.

Light-triggered photoisomerization of the azobenzene (AB) unit in bistable [2]rotaxanes can cause the shuttling of the macrocycle on the dumbbell, resulting in distinctive dual spectral variation characteristics: (1) the spectral change of the photochromic unit and (2) the variation of the charge-transfer band. By employing the CT bond region as an output signal, non-destructive readout of optical information could be achieved.