Synthesis and partial characterization of a new low gap polymer: poly-2(5)-propenylidenepyrrole

As a result of previous studies on the reactivity of 1-selenoallyl cationic species with pyrroles, a synthetic scheme, based on the dramatic solvent effects on the regiochemistry of these reactions, has been devised for the preparation of the polymeric material 6 composed of alternating propenyl and pyrrole units. It is argued that oxidation of 6 using Ph 3CSbCl 6 or DDQ produces the title compound 8 where every other alternating pyrrole ring should have a quinoid structure. In agreement with theoretical predictions of bandgap lowering by these quinoid structure units, preliminary measurements on the undoped and iodine-doped 8 gave conductivity values of δ = 1.1 × 10 −6 and δ = (2.4−5.4) × 10 −6 μ −1 cm −1, respectively.