Introducing inherent chirality in electrochemistry : new electrode surfaces with outstanding enantiorecognition properties and new-concept chiral ionic liquids

The typical design of chiral electroactive materials involves attaching chiral pendants to an electroactive polyconjugated backbone and generally results in modest chirality manifestations. We have designed "inherently chiral" thiophene-based electroactive monomers, where chirality is not external to the electroactive backbone but inherent to it, and results from a torsion generated by the presence of an atropisomeric, conjugatively active biheteroaromatic scaffold. The coincidence of the stereogenic element with the whole electroactive backbone in the starting monomers affords by electrooligomerization enantiopure electrode surfaces with impressive chiroptical activity, finely and reversibly tunable by the electric potential, and with outstanding enantiorecognition ability towards specular redox probes [1]. Besides extending such exciting study, we are now trying to apply the same "inherent chirality" approach to the development of inherently chiral ionic liquids, hopefully endowed with high enantioselectivity, like the formerly developed inherently chiral electrodes. An overview will be given of the first structures obtained and of their electrochemical properties. The new molecules are based on cations including different atropisomeric bis-benzimidazolium groups acting as the stereogenic element, responsible for both the molecular chirality and the IL properties of the material, modulated by number, position and length of alkyl chain substituents. With the contribution of Fondazione Cariplo, grants no. 2011-0417 (inherently chiral electrodes) and no. 2011-1851 (inherently chiral ionic liquids) References [1] F. Sannicolò, S. Arnaboldi, T. Benincori, V. Bonometti, R. Cirilli, L. Dunsch, W. Kutner, G. Longhi, P.R. Mussini, M. Panigati, M. Pierini, S. Rizzo, Angew. Chem. 2014, 53, 2623-2627.