Wide-scope Enantiodiscrimination at Chiral Electrochemical Interphases: Highlighting Structure Effects on Probe-Selector Interactions

Chiral electroanalysis could be regarded as the highest recognition degree in electrochemical sensing, implying the ability to discriminate between specular images of a given electroactive molecule, in terms of peak potential difference. A collection of systematic voltammetry tests is presented here, performed at electrochemical interphases with implementation of inherently chiral selectors (i.e. with the stereogenic element responsible for chirality coinciding with the functional group responsible for the material specific properties [1,2]). In particular, the electrode surfaces were modified with electrodeposited heterocycle-based inherently chiral oligomer films [3-6]. Neat enantiodiscrimination in terms of large, even huge, peak potential differences, specular by inversion of selector configuration, as well as good linear dynamic range for currents (a most desirable combination for development of quali/quantitative electroanalysis protocols) were observed. The approach looks of general validity, since promising results were obtained with various electroactive chiral probes, also of applicative interest, of different chemical nature and bulkiness, like naproxen, ketoprofen, catechin, epicatechin, tryptophan and so on. We will particularly focus on the comparative examination of systematic series of selectors and chiral probes, which can provide key clues concerning the coordination elements involved in the enantiorecognition process, in order to rationalize probe-selector interactions. This would provide a fundamental background for fast optimization of the chiral selector design as well as for the development of effective protocols enabling high performances in qualitative and quantitative electroanalysis of chiral electroactive probes.