Elaboration of a novel conducting polymer substituted by a N ; N -diethylbenzenesulfonamide group capable of S–N cathodic cleavage in both aqueous and nonaqueous media Jean-Franc ßois Pilard a, * , Charles Cougnon a , Jo€ elle Rault-Berthelot b , Alexandra Berthelot b ,C ecile Hubert a , Khoa Tran a a Laboratoire de Chimie Organique Macromol eculaire, Universit e du Maine, Avenue Olivier Messiaen, UMR-CNRS No. 6011, 72000 Le Mans, France b Laboratoire dÕElectrochimie Mol eculaire et MacroMol eculaire, Synth ese et ElectroSynth ese Organiques, Universit e de Rennes I, 263 Avenue du G en eral Leclerc, UMR-CNRS No. 6510, 35042 Rennes Cedex, France Received 27 October 2003; received in revised form 9 January 2004; accepted 12 January 2004 Available online 24 March 2004 Abstract A conducting polymer has been obtained by anodic oxidation of 4-cyclopenta[2,1-b;3,4-b 0 ]dithiophen-4-ylidenemethyl-N ; N -di- ethyl-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. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Electropolymerization; Polycyclopentadithiophene; Cathodic cleavage; Modified electrode; Conducting polymer; Solid phase synthesis 1. Introduction The involvement of conducting polymers in electronic devices or sensors is in constant evolution. Currently, new systems allowing chemical or biological compound recognition such as DNA [1,2] are being developed. Such systems are based on the attachment of organic substrates onto conducting matrices followed by an in- terfacial interaction between the polymer and the solu- tion [3]. Nevertheless, as far as we are concerned, recognition of the duplex formation followed by its re- lease according to a fully electrochemical procedure has not been investigated yet. This challenge would further imply a specific polymer synthesis. In previous work [4–7], we described the synthesis and the electropolymerization of various thiophenes 3-func- tionalized with arylsulfonamide moieties (Scheme 1). We demonstrated that these new polymers could be used in solid phase synthesis processes as soon as both the at- tachment to and the cleavage from the new polymeric supports of the amine groups can be achieved under mild conditions. The anodic polymerization, the electrochemical be- haviour (p- and n-doping processes) of the polymers and the release of various amines or parented derivatives from these new matrices by cathodic S–N cleavage were demonstrated in organic solvents. For each polymers, the cleavage of the S–N bond occurred at more negative potentials than the n-doping process in a potential range of about )2.6 to )3.2 V vs SCE. These 3-substituted arylsulfonamide polythiophenes were studied in aque- ous media. It appears that, though the p-doping process was observed, it was not possible to observe the n- doping processes in aqueous solutions, due to the rather negative potential values of the reduction of the func- tionalized polythiophenes. Moreover, a study of the * Corresponding author. Tel.: +33-243-8330540; fax: +33-243-833- 754. E-mail address: jean-francois.pilard@univ-lemans.fr (J.-F. Pilard). 0022-0728/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jelechem.2004.01.023 Journal of Electroanalytical Chemistry 568 (2004) 195–201 www.elsevier.com/locate/jelechem Journal of Electroanalytical Chemistry