Inherently chiral conducting polymers

The introduction of chirality in organic conjugated polymers has been considered for a wide variety of purposes and applications, i.e. in optics and sensoristics. In this frame, the possibility of coupling electroactivity and enantiorecognition capability is an ambitious goal of the modern chemical research. As commonly reported in literature, chirality in organic semiconductors has mostly been introduced by attaching chiral pendants to the electroactive conjugated backbone through suitable linkers; however, this approach usually leads to poor chirality manifestations. Our strategy regards the development of inherent chiral conducting polymer in particular 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, UV-vis spectroscopy and circular dichroism with in-situ electrochemistry. Positive charge injection, reducing the torsion angle to achieve better p 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. [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, Electrochimica Acta. - ISSN 0013-4686. - ISSN 1873-3859. - 55:27(2010 Nov), 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, Analytical chemistry. - ISSN 0003-2700. - ISSN 1520-6882. - 81:24(2009), 10061-10070.