Widening the Scope of “Inherently Chiral” Electrodes: Enantiodiscrimination of Chiral Electroactive Probes with Planar Stereogenicity

Abstract

A series of planar‐stereogenicity ferrocenes, important as chiral promoters in enantioselective catalysis, is characterized in terms of relationships between structure and electronic properties. The enantiomers of six selected model cases are then successfully discriminated in voltammetry experiments on electrodes modified with electrodeposited inherently chiral oligomer films, in terms of significant potential differences, specular inverting probe or selector configuration. Small substituent changes do not alter the enantiomer peak sequence, but result in significant modulation of peak potential differences, which appear consistent with the availability of chiral/selector matching elements. The present stereogenic plane case, combined with former ones involving stereogenic centers, axes, and/or helices, shows that the inherent chirality strategy in electroanalysis can be effective with all four rigid stereogenic elements.

Characterization of Inherently Chiral Electrosynthesized Oligomeric Films by Voltammetry and Scanning Electrochemical Microscopy (SECM)

“…The chiral oligomer film was electrodeposited onto a polycrystalline gold disk surface, starting from the enantiopure ( S )-BT 2 T 4 monomer and using a protocol analogous to those reported in detail elsewhere [ 8 , 10 , 11 , 12 ]. In brief, repeated oxidative potential cycling at 0.2 V s −1 was performed over the potential region 0–1.4 V vs. Ag/AgCl (KCl, saturated), in a CH 3 CN solution containing 0.5 mM ( S )-BT 2 T 4 and 0.1 M TBAPF 6 , as supporting electrolyte.…”

“…Chemically produced oligomers can also be dropcasted onto the electrode surface [ 9 ]. These oligomer-modified electrodes have displayed outstanding enantiodiscrimination ability for chiral electroactive probes in terms of large potential differences in voltammetric experiments [ 6 , 7 , 9 , 10 , 11 , 12 ].…”

“…In previous works, the electrochemical characterization of these electrodes has been performed considering voltammetry, spectroelectrochemistry and in-situ conductance techniques [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. These techniques normally provide information on the whole and bulk material.…”

Chiral Electrochemistry: Anodic Deposition of Enantiopure Helical Molecules

“…[47] All approaches described here are about introducing chirality on the electrode surface, but one can not forget that the "carrier of chirality" can also be the supporting electrolyte (e. g. chiral ionic liquid [48] ) in which the investigated enantiomers are dissolved. This complementary concept should also be further developed, including the development of novel chiral redox probes [49,50] for better characterization (standardization) of chiral recognition properties at electrode j electrolyte interface.…”

Multimilligram‐scale production implementation of atropisomers of 2,2′‐bis(2,2′‐bithiophene‐5‐yl)‐3,3′‐bithianaphthene

“…The new molecular design appeared winning because electrodes modified with inherently chiral oligomers showed, in cyclovoltammetry experiments, outstanding enantiodiscrimination ability in terms of significant potential differences, specular inverting probe, or selector configuration. Most of the enantiodiscrimination experiments were performed with electrodes modified with ( M )‐ or ( P )‐ BT 2 ‐T 4 (Figure 1) that resulted to be a very versatile selector, being able to discriminate the enantiomers of several chiral analytes differing both in structure 9 and in the nature of the stereogenic element 10 …”