Portugaliae Electrochimica Acta 2010, 28(1), 63-71 DOI: 10.4152/pea.201001063 PORTUGALIAE ELECTROCHIMICA ACTA ISSN 1647-1571 Determination of Trace Metals by Differential Pulse Voltammetry at Chitosan Modified Electrodes R. Malavé Osuna, 1 C. Capel Ferrón, 1 B. Vercelli, 2 V. Hernández, 1,* G. Zotti, 2 J.T. López Navarrete 1 1 Departamento de Química Física, Universidad de Málaga, 29071 Málaga,Spain 2 Institute for Energetics and Interphases-IENI CNR, C.so Stati Uniti 4, 35127 Padova, Italy Received 21 December 2009; accepted 17 March 2010 Abstract Optical, electrochemical and spectroelectrochemical features of a family of triisopropylsilyl (TIPS) end-capped oligothienoacenes from the tetramer to the octamer are studied. The oxidation potentials and the formation and stability of the different oxidized species are influenced by the oligothienoacene chain length. The effect of the steric hindrance caused by the substituents on the π-dimerization of the radical cations is also investigated by comparing a trimethylsilyl (TMS) substituted pentathienoacene with a TIPS substituted one. Keywords: oligothienoacenes, electrochemistry, spectroelectrochemistry. Introduction Fully fused α-oligothiophenes, i.e. oligothienoacenes have been drawing extensive attention during the last few years because they combine the molecular shape of linear acenes, molecules widely studied in organic electronics, with thiophene monomer, which may increase stability and nuclear aromaticity and also may provide points of attachment for solubilizing substituents [1,2]. Their rigid fully planar structure without conformational disorder [3-6] generates densely packed structures in solid state (beneficial for reaching high charge- carrier mobility), what makes them ideal candidates to be used in a wide range of electronic and opto-electronic applications, including field effect transistors (FETs) [7-9] and light emitting diodes (LEDs) [10]. However, their structural rigidity leads to reduced solubility with regard to their non-fused α-oligothiophene counterparts. To solve this problem, the most * Corresponding author. E-mail address: hernandez@uma.es