Electrochemical properties of a series of substituted oligothiophenes containing vinylphenyl group

Electrochemical studies on oxidation mechanism of thiophene derivatives are reported. Three compounds were investigated: (4,4-didecyloxy[2,2';5', 2]terthiophen)-3'-ylvinylbenzene (ThD); (E,E) 1-cyano-4-(2,5-bis(2- thiophen-2-ylvinyl)-thiophen-3-ylvinyl)benzene (ThV); (E,E) 1-cyano-4-(2,5- bis(2-(5-methyl-thiophen-2-yl)vinyl)thiophen-3-ylvinyl)benzene (ThVMe). Structural differences of these molecules make it possible to find correlations between a particular structure of the molecule and its electrochemical behaviour during oxidation process. ThD was found to polymerize easily and its polymer film is stable. Th V that contains vinyl bonds separating thiophene rings polymerisation appears to be more difficult, only formation of oligomers was possible. Molecule of Th VM, in which outer thiophene rings are terminated with methyl groups in their a, a'- positions cannot polymerize, instead two clearly irreversible redox processes are observed in cyclic voltammetry.