Wide-Scope Enantioselective Voltammetry: Testing Inherently Chiral Selectors With Chiral Probes Representative Of Different Stereogenic Elements

Enantioselective electroanalysis is an advanced, attractive target of high potential interest in applicative fields like e.g. the pharmaceutical one. Of course, since specular molecules have the same properties excepting when interacting with a chiral environment, enantiodiscrimination can only be achieved with the electron transfer process taking place at a chiral electrode|medium interphase. In this frame, remarkable performances have been recently observed employing selectors endowed with "inherent chirality", i.e. in which chirality and key functional properties originate from the same element. Successful chiral voltammetry tests have been obtained (a) on chiral electrode surfaces based on inherently chiral, electroactive heterocycle-based oligomers, including cyclic ones [1-4] and (b) on achiral electrodes in inherently chiral ionic liquids or achiral ionic liquids with inherently chiral additives [5]. An attractive feature of the above approach is its general validity. In fact, we have observed that a given inherently chiral selector can discriminate the enantiomers of even very different chiral probes (and, symmetrically, the enantiomers of a given probe can be discriminated by different inherently chiral selectors). Moreover, enantiodiscrimination by inherently chiral selectors is being tested with chiral probes representative of different classes of stereogenic elements. A selection of examples will be presented, compared and discussed. The current support of Fondazione Cariplo/Regione Lombardia "Avviso congiunto per l’incremento dell’attrattività del sistema di ricerca lombardo e della competitività dei ricercatori candidati su strumenti ERC - edizione 2016” (Project 2016-0923) to our inherently chiral research is gratefully acknowledged. [1] Angew. Chem. Int. Ed. 53 (2014) 2623-2627. [2] Chem-Eur. J. 20 (2014) 15261-15634. [3] Chem. Sci. 6 (2015) 1706-1711. [4] Chem-Eur. J. 22 (2016) 10839-10847. [5] Angew. Chem. Int. Ed. 56 (2017) 2079 –2082.