Data di Pubblicazione:
2013
Citazione:
Inherently chiral conducting polymer film electrodes / F. Sannicolò, V. Bonometti, S. Arnaboldi, M. Magni, P.R. Mussini, W. Kutner, K. Noworyta, T. Benincori, S. Rizzo, R. Cirilli, M. Panigati. ((Intervento presentato al 17. convegno AISEM Associazione Italiana Sensori e Microsistemi tenutosi a Brescia nel 2013.
Abstract:
In the last years we have been developing and characterizing “spider-like” oligothiophenes[1][2], to
develop novel functional materials for energy and sensor applications, and to throw new light on the
structure/reactivity relationships in the important class of oligothiophene semiconductors.
When present, distortions from planarity (“nodes”) along the main conjugated chain impair the
conjugation efficiency of the system, and lead to an increase in the HOMO-LUMO gap that limits
the possible applications in the energetic field. However, the intrinsic 3D character of the nodes can
also be advantageously exploited, as in the case of the purposedly non-planar multithiophene-based
monomer TBTX (Figure 1)[3], displaying a 70° distortion around the central bond. Its intrinsically
high ability for fast and regular electropolymerization allowed its use as a 3D promoter building
block in copolymerizations, particularly with co-monomers endowed with key functional properties:
a co-polymer, deposited by electropolymerisation of racemic TBTX together with a monomer
bearing a crown-ether function (Figure 2), was found to outstandingly perform as the recognition
element of a molecularly imprinted piezomicrogravimetric chemosensor for the determination of
melamine, of high selectivity and sensibility, that has been patended and published[4][5].
Moreover, calculations revealed that the barrier to rotation around the central bond is very high,
suggesting that TBTX exists as a pair of configurationally stable antipodes: thus, chirality is an
inherent property of the whole molecule, which is devoid of carbon stereocentres. Actually TBTX
enantiomers have been quantitatively and easily separated by chiral HPLC, and experiments of
enantiomer TBTX electropolymerizations have been performed. The enantiopure specular
conducting polymer films have been characterized together with the racemate one by CV, EIS,
spectroelectrochemistry and circular dichroism with in-situ electrochemistry. Positive charge
injection, reducing the torsion angle to achieve better π-system conjugation, results in a fully
reversible "breathing" process of the 3D chiral conducting network upon potential cycling (Figure 3)
The availability of materials able to couple electroactivity and enantiorecognition capability is an
ambitious objective of the current chemical research, aiming to both electrically triggered
enantioselective electron transfers and electrically monitored enantioselective recognitions. In this
light, enantiorecognition tests on the enantiopure chiral polymer surfaces (particularly
electrodeposited in ionic liquid on screen printed electrodes, to improve regularity and
reproducibility) are in progress with interesting preliminary results [6].
Tipologia IRIS:
14 - Intervento a convegno non pubblicato
Elenco autori:
F. Sannicolò, V. Bonometti, S. Arnaboldi, M. Magni, P.R. Mussini, W. Kutner, K. Noworyta, T. Benincori, S. Rizzo, R. Cirilli, M. Panigati
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