Electrodeposition of thiophene-based inherently chiral electrodesurfaces: from traditional media to RTILs

Thiophene-based inherently chiral conducting films, under development in our research group, have very high and stable chiral activity, depending on a tailored torsion of the whole conducting backbone rather than on attached chiral pendants; accordingly, such chirality is modulable by the amount of injected charge (reducing the torsion angle to achieve better p system conjugation), a phenomenon which suggested us the image of a breathing system. Perfectly specular electrode surfaces have been prepared by electrodeposition cycles, starting from the corresponding inherently chiral oligomers, and their enantiorecognition ability is currently under study in our group. In order to finely discriminate among the racemate and enantiomer film properties, and above all to achieve optimized enantiomer electrode surfaces for applications as chiral sensors, reproducibility is a necessary but hard task. In this context, preliminary literature studies [1,2] pointed to room temperature ionic liquids RTIL, both as such and as cosolvents, significantly improving the regularity and the mechanical and morphological properties of the conducting films to be employed e.g. in the energetic, optoelectronic, and sensoristic domains (besides other advantages including negligible vapour pressure, high intrinsic conductivity without addition of supporting electrolyte and easy recyclability). In this frame, we will present our recent extensive study aimed to the rationalization of the conducting film features obtained in different conditions (i.e., RTILs vs non polar and polar VOCs, on various electrode), both on model starting monomers (EDOT and EDOP) and on our newly developed inherently chiral ones. References: [1] F. Endres, A.P. Abbott, D.R. MacFarlane, Electrodeposition from Ionic Liquids, 2008, Wiley-VCH, ISBN 978-3-527-31565-9. [2] A.Pietrzyk, W.Kutner, R.Chitta, M. E. Zandler, F. D’Souza, F. Sannicolò, P.R. Mussini, Anal. Chem., 2009, 81(24), 10061-10070.