Electronic and structural consequences of n-doping: bithiazole oligomers and partially reduced bithiazolium cations

N-methylated-poly(diakyl-bithiazoles), NPABTs, can be reduced to give reasonably stable n-doped polymers. In order to understand the changes in the electronic structure and polymer conformations upon reductive doping of NPABTs, a series of oligomers of increasing length was studied by self-consistent field (AM1) and configuration interaction (ZINDO/S) calculations. Large red shifts in the optical transitions are predicted upon n-doping, along with significant planarization of chain segments. Full planarization was not realized for n-doped materials, however, as a variety of localized units were observed.