Conducting polymers containing peri-xanthenoxanthenes via oxidative cyclization of binaphthols

We report an electrochemical transformation of binaphthols to give peri-xanthenoxanthene (PXX) groups in small molecules and within polymer backbones. The monomer 7,7-bis(2,2-bithiophen-5-yl)-1,1-bi-2,2-naphthol (2) was subjected to electropolymerization, resulting in the segmented conducting polymer that is stable at low potentials. However, high-potential electrochemical oxidation promoted cyclization of binaphthol units gives PXX, which transforms the moderately conducting segmented polymer into a highly conducting fully conjugated polymer. This oxidative cyclization is a highly effective means by which to incorporate a planar polycyclic heteroaromatic structure (i.e., PXX) into thiophene-based conducting polymers. A model compound study conclusively proved the proposed oxidative cyclization scheme.