Synthesis and electropolymerization of new p-nitrophenyl-functionalized thiophene derivatives

Electrooxidative polymerization of three new p-nitrophenyl-functionalized t hiophene derivatives leads to materials which show the electroactivities of both nitrobenzene and polythiophene. However, other than the reversible re dox transition in solution, the nitro groups exhibit a complex nature of th e cyclic voltammetric curve in the obtained solid polymeric films. It was f ound that the electrochemical behavior of the nitro groups has a dramatic e ffect on the conjugated pi-electron systems of the substituted polythiophen es. Upon electrochemical addressing of the nitro groups the electroactiviti es of the corresponding polymers decrease rapidly compared to their analogo us polymers without nitro groups. FTIR studies of these polymers revealed t hat after the reduction/oxidation process of the nitro groups still a large amount of electrolyte salt remains in the polymer films. As typical of fun ctionalized polythiophenes, however, these new polymers can be switched und er controlled conditions between their oxidized and neutral forms and exhib it the typical properties of electroactive polythiophenes, e.g., electrochr omism.