Wireless Hollow Miniaturized Objects for Electroassisted Chiral Resolution

Abstract

Chiral resolution plays a crucial role in the field of drug development, especially for a better understanding of biochemical processes. In such a context, classic separation methods have been used for decades due to their versatility and easy scale-up. Among the many attempts proposed for enantioselective separation, electroassisted methods are presented as an interesting alternative. Herein, we present the use of wirelessly activated hollow tubular systems for the effective, simple, and tunable separation of racemic and enantioenriched mixtures. These double-layered tubular objects consist of an external polypyrrole chassis, a polymer with good electromechanical properties, functionalized in its inner part with an inherently chiral oligomer. The synergy between the electromechanical pumping process of the outer layer and the enantioselective affinity of the inner part induces the system to behave as a miniaturized chiral column. These hybrid objects are able to separate racemic and enantioenriched solutions of chiral model analytes into the corresponding enantiomers in high enantiomeric purity. Finally, these electromechanical systems can resolve mixtures formed by chiral probes with completely uncorrelated molecular structures injected simultaneously into the single antipodes.

Unconventional approaches for chiral resolution

“…This approach takes advantage of two main ingredients: (1) a wireless electromechanical pumping effect and (2) the outstanding enantiorecognition of inherently chiral oligomers. In this work, a chiral tubular hollow electro-pump constituted by a polymeric bilayer was designed [ 68 , 69 ]. This device was obtained in a two-step approach; at first, the electrooligomerization of the inherently chiral monomer (BT 2 T 4 ) (Fig.…”

“…The presence of the enantiopure oligo-BT 2 T 4 affects the retention time of the chiral analyte injected inside the modified Ppy tube; thus, for favorable diastereomeric interaction, the chiral probe remains trapped inside the tube, whereas for unfavorable interaction, the analyte is expelled almost immediately. Furthermore, these devices were used for the highly efficient enantioseparation of mixtures of racemates and unbalanced samples containing two chiral analytes with uncorrelated chemical structures [ 69 ]. The HPLC analyses of the collected fractions corroborate the outstanding enantioseparation, obtaining samples with high enantiomeric purity (ee > 90%) (Fig.…”

“…The green and red colors stand for the ( S )- and ( R )-carvone, respectively, whereas the yellow and blue colors represent the ( S )- and ( R )-N, N-dimethyl-1-ferrocenylethylamine, respectively. Adapted from reference [ 69 ] …”