title: Tetrathiafulvalene radical cation dimerization in a bistable tripodal [4]rotaxane.
abstract: The template-directed synthesis of a bistable tripodal [4]rotaxane, which has cyclobis(paraquat-p-phenylene) (CBPQT4+) as the pi-electron-deficient rings, and tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene units as the pairs of pi-electron-rich recognition sites located on all three legs of the tripodal dumbbell, is described. The chemical and electrochemical oxidation of the [4]rotaxane and its tripodal dumbbell have allowed us to unravel an unprecedented TTF.+ radical cation dimerization. In fact, two types of TTF dimers, namely, the radical cation dimer [TTF.+]2 and the mixed-valence one [(TTF)2].+, have been observed at room temperature for the tripodal dumbbell, whereas, in the case of the [4]rotaxane, only the radical cation dimer [TTF.+]2 is formed. This anomaly can be explained if it is accepted that most of the neutral TTF units in the [4]rotaxane are encircled by CBPQT4+ rings, which renders the formation of the mixed-valence dimer [(TTF)2].+ highly unfavorable.
authors: The California NanoSystems Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA.
authors: Ivan
authors: I
authors: Aprahamian
authors: John-Carl
authors: JC
authors: Olsen
authors: Ali
authors: A
authors: Trabolsi
authors: J Fraser
authors: JF
authors: Stoddart