ELECTROOXIDATION OF SUBSTITUTED CONJUGATED SEXITHIENYLS

A new series of conjugated alpha-sexithienyls derivatized by alkyl and oxyalkyl groups has been synthesized. Although of comparable electronic inductive effects, these substituents produce important differences in the electrochemical behavior of the pi-conjugated system. Long alkyl or oxyalkyl chains lead to an enhancement of electrochemical reversibility and a stabilization of the cation radical state. The electrodeposition of these oligomers has been achieved by means of recurrent potential scans. Analysis of the electrodeposition process and of the electrochemical behavior of the resulting materials suggests that, whereas in polar solvents radical coupling occurs and leads to extensively conjugated polymers, in methylene chloride electrodeposition seems to proceed via the di-cation state and to produce essentially the corresponding di-cation salt.