Oligothienylenevinylene Polarons and Bipolarons Confined between Electron-Accepting Perchlorotriphenylmethyl Radicals

A detailed analysis is undertaken of positively charged species generated on a series of thienylenevinylene (nTV) wires terminally substituted with two perchlorotriphenylmethyl (^. PTM) radical acceptor groups, ^. PTM-nTV-PTM^. (n=2-7). Motivated by the counterintuitive key role played by holes in the nTV bridges on the operating mechanism of electron transfer in their radical anion mixed-valence derivatives, a wide combination of experimental and theoretical techniques is used, with the aim of gaining further insights into their structural location. Consequently, contributions of the ^. PTM units for the stabilization of the radical cations and hole localization, particularly in the case of the shortest molecular wire, are probed. In this sense, the formation of quinoidal ring segments, resulting from the coupling of the unpaired electron of the ^. PTM radical site with those generated along the nTV chains is found. Additionally, open-shell dications, described by the recovery of the central aromaticity and two terminal quinoidal segments, assisted by the ^. PTM units, are detected.