Thiahelicene-based inherently chiral films for enantioselective electroanalysis

Chiral electroanalysis could be regarded as the highest recognition degree in electrochemical sensing,
implying the ability to discriminate between specular images of an electroactive molecule, particularly in
terms of significant peak potential difference. A groundbreaking strategy was recently proposed, based
on the use of “inherently chiral” molecular selectors, with chirality and key functional properties
originating from the same structural element. Large differences in peak potentials have been observed
for the enantiomers of different chiral molecules, also of applicative interest, using different selectors, all
of them based on atropisomeric biheteroaromatic scaffolds of axial stereogenicity. However, helicene
systems also provide inherently chiral building blocks with attractive features. In this paper the
enantiodiscrimination performances of enantiopure inherently chiral films obtained by electrooxidation
of a thiahelicene monomer with helicoidal stereogenicity are presented for the first time. The
outstanding potentialities of this novel approach are evaluated towards chiral probes with different
chemical nature and bulkiness, in comparison with a representative case of the so far exploited class of
inherently chiral selectors with axial stereogenicity. It is also verified that the high enantiodiscrimination
ability holds as well for electron spins, as for atropisomeric selectors.