One-dimensional energy/electron transfer through a helical channel.

We have synthesized A-D-A-type linear chain chromophores based on oligo(phenylene vinylene) as an electron donor (D) and several electron/energy acceptors (A), which are linked by an alkyl spacer with various lengths and are processed for a helical encapsulation with amylose. Photoinduced electron/energy transfers (eT/ET) of the chromophores are investigated in the presence and absence of the helical encapsulation with respect to D-A distance. Fluorescence intensity of the free chromophores is unusually small, not due to the advancement of eT/ET but most likely to self-quenching by aggregation and/or conformational flexibility in solution. By contrast, the helically encapsulated chromophores exhibit highly efficient eT/ET over a long D-A distance and a well-defined distance effect depending on the acceptor strength.