Low-Band-Gap Conjugated Polymers. Improved Model Compounds for the Structural Analysis of Poly(isothianaphthene)

The simulation of the structure of aromatic and quinoid poly(isothianaphthene) (PITN) has been improved, by the synthesis of new model compounds. The C-13 NMR investigation confirms our previous results that the geometric structure of this low-band-gap conducting polymer shows a strong quinoid character. For the aromatic structure, 1,3-dithienylisothianaphthene and a series of disilylated isothianaphthene oligomers were synthesized. trans-3,3'-Bibenzo[c]thienylidene was prepared in order to model the quinoid structure. All these new model compounds simulate better neighboring S-atom effects, a structural feature which was not accounted for in the previously reported model compounds.