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A conducting polymer has been obtained by anodic oxidation of 4-cyclopenta[2,1-b;3,4-b′]dithiophen-4-ylidenemethyl-N,N-diethyl-benzenesulfonamide. In this novel polycyclopentadithiophene matrix, a cathodically sensitive aryl sulfonamide group is grafted through an ethylene junction to the polymer backbone. This polymer exhibits a remarkable electroactivity in organic and aqueous solvents allowing a smooth electrochemical cleavage of the S–N bond in both media.

New thiophene derivatives substituted by electrochemically cleavable sulfonamide groups have been synthesised and their electrochemical behaviour has been investigated in acetonitrile. The anodic oxidation of phenyl (I)- and naphthyl (II)sulfonamide-substituted thiophenes yielded corresponding polymer films exhibiting p- and n-doping processes. The cathodic cleavage of the SN bond grafted to the polymer backbone was performed by applying a potential lower than −2.5 V (versus Ag ∣ 10−1 M Ag+) to the polymer. The efficiency of this solid-state electrochemical reaction was found to be strongly lowered when the film thickness was increased. It was demonstrated that the decrease of this parameter was less important when a copolymer electroformed from II or a phenylsulfonamide-substituted terthiophene (III) was involved. The recycling properties of this type of material were illustrated by the grafting of an aminoferrocene moiety after the cathodic cleavage step to poly(II-co-3-methylthiophene).