The effect of structural changes on the electronic properties of poly(isothianaphthene) derivatives

Summary form only given. Structure analysis of conducting polymers is complicated by the insoluble, infusible and amorphous character of these materials. In order to obtain a better understanding of structure-properties relationships a profound structure analysis remains essential. A possible strategy to solve this problem consists in comparing suitable modelcompounds with the corresponding polymer. These modelcompounds should simulate the polymer structure as close as possible, be stable and preferably soluble in NMR-solvents. In our laboratory this method was succesfully applied to determine the structure of poly(isothianaphthene). To study the effect on the electronic structure by changing the chemical structure of poly(isothianaphthene), we need a modelcompound in which it is easy to substitute carbon nuclei by heteroatoms or to replace hydrogen nuclei by substituents. Compaing 1,3-dithienylisothianaphthene (DTI) with an ideal aromatic modelcompound, an isothianaphthene tetramer, we show DTI to be a fairly good modelcompound. Our goal is to use DTI derivatives as modelcompounds to study the effect of structural changes on the electronic properties of corresponding polymers. Therefore we developped first of all a possible general applicable synthetic route to DTI derivatives. Good results were obtained by a Grignard reaction on o-S-(2-pyridyl) thiophtalate followed by a classical ring closure with P/sub 4/S/sub 10/ . The general application of this route to other DTI derivatives, such as nitrogen and fluorine substituted compounds, is under investigation and could show the way to a whole series of easy accesible modelcompounds for structural analysis of conducting polymers as well as to a new class of isothianaphthene based conducting ´co´- polymers with very promising electronic properties. The structure of these ´co´-polymers will be investigated using advanced NMR-techniques and FT-Raman spectroscopy.