Synthesis and characterisation of poly(isothianaphthene methine).

The reaction of 4-hexyloxybenzaldehyde and 1,3-t-butyldimethylsilylisothianaphthene in POCl3 yields a soluble poly(isothianaphthene methine) derivative (1). This polymer is stable as well in the undoped as doped state and shows good reversible electrochromic properties. With a band gap of 1.2 eV this polymer can be considered as a low bandgap material. The oxidation potential of 375 mV against Ag-wire is one of the lowest reported for a conjugated polymer.