Enantiodiscrimination at electrochemical interphases though implementation of chiral and inherently chiral selectors : novel insights and perspectives

Congresso online a causa della pandemia (doveva originariamente tenersi a Belgrado) Enantiodiscrimination at electrochemical interphases through implementation of chiral and inherently chiral selectors: novel insights and perspectives Patrizia Romana Mussini,a Serena Arnaboldi,a Sara Grecchi,a Mirko Magni,a Mariangela Longhi,a Francesco Orsini,a Giovanna Longhi,b Roberto Cirilli,c Fabiana Arduini,d Laura Micheli,d Claudio Fontanesi,e Marcus Korb,f Heinrich Lang,f Emanuela Licandro,a Silvia Cauteruccio,a Simona Rizzo,g Lorenzo Guazzelli,h Andrea Mezzetta,h Tiziana Benincorii a Università degli Studi di Milano, Milano, Italy; bUniversità degli Studi di Brescia, Brescia, Italy; cIstituto Superiore di Sanità, Roma, Italy; dUniversità degli Studi di Roma Tor Vergata, Roma, Italy; eUniversità di Modena e Reggio Emilia, Italy; fTechnische Universität Chemnitz, Germany; gCNR ISTM, Milano, Italy; hUniversità degli Studi di Pisa, Pisa, Italy iUniversità degli Studi dell'Insubria, Como, Italy Mail to: Patrizia R. Mussini, Università degli Studi di Milano, Dipartimento di Chimica, Via Golgi 19, 20133 Milano (Italia) patrizia.mussini@unimi.it To achieve enantioselectivity, electron transfer processes at the electrochemical interphase require the presence of a suitable enantiopure chiral selector, resulting in energetically different diastereoisomeric con¬di¬tions for the two probe enantiomers.1 A groundbreaking strategy is based on the use of molecular selectors endowed with "inherent chirality", i.e. with chirality and key functional pro¬perties originating from the same structural element, which in our case identifies with the main mo¬le¬cular backbone, fea-turing a tailored torsion with a racemization energy barrier too high to be overcome at room temperature. Large peak potential differences have been observed in voltammetry for the enan¬tiomers of even very different chiral probes either (i) working in achiral media, on electrode surfaces modified with thin films of inherently chiral electroactive oligomers1-4 or (ii) working on achiral electro¬des, implementing inherent chirality in the medium, particularly in ionic liquids ILs, either chiral them¬selves, or modified by a chiral additive,1,5,6 exploiting the peculiar IL high order at the interphase with a charged electrode. Both strategies are being now extended and refined, particularly aiming to collect clues for the elucidation of the recognition mechanism, as well as to highlight attractive applications. In the film case, we are studying in detail morphology, growth, chemical composition as well as functional properties of inherently chiral electroactive oligomer films, both as electrode surfaces and as self-standing membranes. In the media case, chiral or inherently chiral molecules are being studied as advanced media and/or media additives/components, with impressive results. Overall a wide palette of selectors (film or media) and/or probes are being compared, representing four classes of ste¬reogenic elements, i.e. stereogenic centres, axes, planes and helixes. The outstanding enantiodicrimination ability of the new selectors is also being considered beyond molecular chiral probes, i.e. towards polarized light components (in terms of circular dichroism and circularly polarized luminescence) and electron spins (in magnetoelectrochemistry experiments). Not only impressive effects have been observed, but fascinating correlations and connections are emerging among the three areas, worthy to be explored in detail, possibly providing further interpretative clues, as well as for possible exploitation in photonics and spintronics.. Advice from Prof. F. Sannicolò as well as support from Regione Lombardia and Fondazione Cariplo (particularly Project 2016-0923) and Università degli Studi di Milano is gratefully acknowledged. [1] S. Arnaboldi, M. Magni, P. R. Mussini, Curr. Opin. Electrochem., 2018, 8, 60-72. [2] 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. Int. Ed., 2014, 53, 2623-2627. [3] S. Arnaboldi, T. Benincori, R. Cirilli, W. Kutner, M. Magni, P.R. Mussini, K. Noworyta, F. Sannicolò, Chem. Sci. 2015, 6, 1706-1711. [4] S. Arnaboldi, T. Benincori, A. Penoni, L. Vaghi, R. Cirilli, S.Abbate, G.Longhi, G.Mazzeo, S. Grecchi, M. Panigati, P. R. Mussini Chem. Sci., 2019, 10, 2708-2717. [5] S. Arnaboldi, D. Vigo, M. Longhi, F. Orsini, S. Riva, S. Grecchi, E. Giacovelli, V. Guglielmi, R. Cirilli, G. Longhi, G. Mazzeo, T. Benincori, P.R. Mussini, ChemElectroChem 2019, 6 (16) 4204-4214. [6] S. Rizzo, S. Arnaboldi, V. Mihali, R. Cirilli, A. Forni, A. Gennaro, A.A. Isse, M. Pierini, P.R. Mussini, F. Sannicolò, Angew. Chem. Int. Ed., 2017, 56, 2079-2082. [7] M. Longhi, S. Arnaboldi, E. Husanu, S. Grecchi, I. F. Buzzi, R. Cirilli, S. Rizzo, C. Chiappe, P. R. Mussini, L. Guazzelli, Electrochim. Acta 2019, 298, 194-20.