Polyheterocycles containing alkene spacer linkages. 2. Synthesis and polymerization of (E)-2-styrylthiophenes and (E)-2-styrylpyrrole

A number of (E)-2-styrylthiophenes, exhibiting a range of electronic effects, and (E)-2-styrylpyrrole were synthesized and their electrochemical behaviour investigated. The films, produced by anodic electropolymerization, were redox inactive and exhibited conductivities of the order of 10(-6) S cm(-1). The nature of the films was investigated by electrochemical, spectroscopic and microscopic techniques. The low conductivities exhibited by these films may be attributed to oxidation of the alkene spacer linkage resulting in a crosslinked polymeric matrix. Solid-state NMR, FT-IR and photoacoustic-IR confirmed the presence of saturated carbon atoms which would inevitably lead to a decrease in conjugation length. However, in all cases, stable coherent films were obtained from the electropolymerization reaction and an exceptionally smooth film of 20 mu m in thickness could be grown from (E)-2-styrylpyrrole on ITO glass.