Communication www.rsc.org/chemcomm CHEMCOMM Formation and electrochemical desorption of stable and electroactive self-assembled monolayers (SAMs) of oligothiophene–fulleropyrrolidine dyads Sheng-Gao Liu, ac Corinne Martineau, b Jean-Manuel Raimundo, b Jean Roncali* b and Luis Echegoyen* a a Department of Chemistry, University of Miami, FL 33143, USA. E-mail: echegoyen@miami.edu b Ingénierie Moléculaire et Matériaux Organiques, UMR CNRS 6501, Université d’Angers, 2 Bd Lavoisier, 49045 Angers Cedex, France c National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80401-3393, USA Received (in Columbia, MO, USA) 17th January 2001, Accepted 21st March 2001 First published as an Advance Article on the web 1st May 2001 Stable, electroactive SAMs of oligothiophene–fulleropyrroli- dine dyads have been prepared by spontaneous adsorption; electro-oxidation of the oligomeric system results in desorption. Self-assembled monolayers (SAMs) provide unique opportuni- ties to develop chemically tailored surfaces with specific chemical and physical properties. 1,2 Besides the considerable amount of work devoted to the development of selective electrochemical sensors, 1,2 SAMs have attracted increasing interest due to potential use in molecular electronics. 3 In this context, there have been several reports concerning the preparation and characterization of SAMs derived from various kinds of linear p-conjugated oligomers on gold surfaces. 3–5 However, until now, all of these monolayers were prepared from oligomeric systems possessing one or two terminal alkanethiol groups eventually connected to the conjugated system via a flexible alkyl spacer. Recently, this approach has been successfully applied to the preparation of SAMs of C 60 - derivatized oligothiophenes. 5 On the other hand, despite some theoretical controversy, the adsorption of thiophene onto Au(111) was recently demonstrated. 6 Here, we show for the first time that stable SAMs can be produced on Au(111) surfaces by spontaneous adsorption of C 60 -derivatized, p-conjugated oligomers of the thiophene and thienylenevinylene 7 series. Although the fulleropyrrolidine group represents a very convenient electroactive probe, its role in the process of SAM formation is not clearly elucidated at the present time. Compounds 1–6 (Chart 1) were newly synthesized by reacting the appropriate carbaldehyde with C 60 in the presence of N-methylglycine according to the methodology of Prato and coworkers 8 with a slight modification as reported for the synthesis of C 60 –thiophene dyads by ourselves. 9 All new compounds were fully characterized by the usual spectroscopic and analytical techniques giving satisfactory results.† SAMs were prepared by dipping ultra-clean, spherical, gold (99.9999%) bead electrodes‡ for 24–72 h in 1 mM o- dichlorobenzene (ODCB) solutions of compounds 1–6. The electrodes were then thoroughly rinsed with ODCB and CH 2 Cl 2 , dried under an argon flow and immersed in 0.05 M Bu 4 NPF 6 –ODCB for electrochemical characterization. Sonica- tion in ODCB did not remove the SAMs, indicating that the compounds are chemically adsorbed and not simply phys- isorbed. The cyclic voltammogram (CV) of a SAM of 3 (Fig. 1) shows two well-resolved reversible cathodic waves with E 0 1 = 20.65 V and E 0 2 = 21.04 V corresponding to the first two one- electron reductions of the C 60 fragment. 10 Scanning the potential to 21.8 V (vs. Ag/AgCl) allowed the observation of the reversible third reduction at 21.57 V (not shown in Fig. 1 due to an impurity present in OBCD at around 21.2 V). Within Chart 1 Fig. 1 CVs of a SAM of 3 in 0.05 M Bu 4 NPF 6 –ODCB system, scan rates between 100 (smallest current) and 1000 (largest current) mV s 21 . This journal is © The Royal Society of Chemistry 2001 DOI: 10.1039/b102132j Chem. Commun., 2001, 913–914 913 Downloaded by Universitaire d'Angers on 20 December 2012 Published on 01 May 2001 on http://pubs.rsc.org | doi:10.1039/B102132J View Article Online / Journal Homepage / Table of Contents for this issue