Choosing sides: unusual ultrafast charge transfer pathways in an asymmetric electron-accepting cyclophane that binds an electron donor

Constructing functional molecular systems for solar energy conversion and quantum information science requires a fundamental understanding of electron transfer in donor-bridge-acceptor (D-B-A) systems as well as competitive reaction pathways in acceptor-donor-acceptor (A-D-A) and acceptor-donor-acceptor' (A-D-A') systems. Herein we present a supramolecular complex comprising a tetracationic cyclophane having both phenyl-extended viologen (ExV ) and dipyridylthiazolothiazole (TTz ) electron acceptors doubly-linked by means of two -xylylene linkers (TTzExVBox ), which readily incorporates a perylene (Per) guest in its cavity (Per ⊂ TTzExVBox ) to establish an A-D-A' system, in which the ExV and TTz units serve as competing electron acceptors with different reduction potentials. Photoexcitation of the Per guest yields both TTz ˙-Per ˙-ExV and TTz -Per ˙-ExV ˙ in