Synthesis and polymerization of 2- and 3-substituted thiophene derivatives linked by polyether bridges

New compounds consisting of 2- and 3-thienyl units linked by polyether bridges have been synthesized and their electrochemical polymerization was performed via constant potential electrolysis (CPE) in an electrolytic solution containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) dissolved in CH3CN. 2-Thienyl monomers (I and II), but not 3-thienyl monomers (III and IV), were also polymerized via chemical oxidation, which yielded broken π-conjugated polymer products. The polymers were characterized using 1H NMR and FT-IR spectroscopic techniques. It was found that both chemical and electrochemical oxidation of 2-thienyl monomers gave mainly poly(2,2′-bithiophenemethylene) due to elimination of polyether chains during the polymerization reaction. On the other hand, electrochemical oxidation of 3-thienyl monomers resulted in corresponding polymers without any cleavage of polyether bridges. Spectroelectrochemical (SPEL) properties of the products were investigated using UV–Vis spectroscopic techniques.