Inherently chiral conducting polymer film electrodes

Molecular materials coupling electroactivity with enantiorecognition capability are an ambitious objective of the current chemical research, aiming to both electrically triggered enantioselective electron transfers and electrically monitored enantioselective recognitions. Ideal candidates are organic conducting polymers, several of which have been functionalized with chiral pendants; this "localized" approach, however, appears to lead to poor chirality manifestations. We present inherently chiral conducting polymer films prepared by electropolymerization of monomers like the TBTX molecule [1] (already applied as a racemate as 3-D promoter comonomer for the electrosynthesis of very efficient MIP films [2]), where chirality is owed to a tailored torsion internally produced along the whole conjugated backbone by insertion of a suitable biheteroaromatic core, and not to the presence of stereocentres external to the conjugated chain (Figure 1). Both enantiomer films have been characterized together with the racemate one by electrochemical methods and by UV-vis spectroscopy and circular dichroism with in-situ electrochemistry. Positive charge injection, reducing the torsion angle to achieve better pi system conjugation, results in a fully reversible "breathing" process of the 3D chiral conducting network upon potential cycling. Enantiorecognition capability tests on chiral probe molecules are in progress. References [1] An effective multipurpose building block for 3D electropolymerisations:2,2’-bis(2,2’-bithiophene-5-yl)-3,3’-bi-1-benzothiophene / F. Sannicolò, S. Rizzo, T. Benincori, W. Kutner, K. Noworita, J.W. Sobczak, V. Bonometti, L. Falciola, P.R. Mussini, M. Pierini. - In: Electrochimica Acta. - ISSN 0013-4686. - ISSN 1873-3859. - 55:27(2010 Nov), pp. 8352-8364. [2] Melamine Acoustic Chemosensor Based on Molecularly Imprinted Polymer Film / A.Pietrzyk, W.Kutner, R.Chitta, M. E. Zandler, F. D’Souza, F. Sannicolò, P.R. Mussini. - In: Analytical chemistry. - ISSN 0003-2700. - ISSN 1520-6882. - 81:24(2009), pp. 10061-10070.