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 tests is presented here, focusing on the specific interactions between systematic series of selectors and chiral probes, suggesting interesting clues about the corresponding elements involved in the enantiorecognition process. In particular, voltammetric experiments were performed at chiral electrochemical interphases with implementation of inherently chiral (with the stereogenic element responsible for chirality coinciding with the functional group responsible for the material specific properties [1,2]) or chiral selectors, according to two strategies: i) use of electrode surfaces modified with electrodeposited heterocycle-based inherently chiral oligomer films [3-6]; ii) use of enantiopure chiral media of high intrinsic order [7-9]. In all cases neat enantiodiscrimination, in terms of 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, confirming the general validity of this strategy. The novel approach looks of wide applicability in terms of chiral probes, since promising results, were obtained, testing (inherently) chiral selectors, for enantiodiscrimination of many relevant chiral molecules, also of applicative interest, with different chemical nature and bulkiness, like naproxen, ketoprofen, catechin, epicatechin, tryptophan and many others. The overall effectiveness of inherent chirality selectors is thus confirmed, since they work in all cases with different electroactive chiral probes. However, the rationalization of the probe-selector interactions suggests interesting clues about the corresponding elements involved in the enantiorecognition process and therefore being able to obtain the best performances. This combination provides a most desirable background for the development of effective protocols for qualitative and quantitative electroanalysis of chiral electroactive probes.