ENANTIOSEPARATION OF CHIRAL COMPOUNDS CONTAINING EXTENDED pai-ELECTRON CLOUDS

In the last decade, planar chiral ferrocenes have attracted a growing interest in several fields, particularly in asymmetric catalysis, medicinal chemistry, chiroptical spectroscopy and electrochemistry [1]. Despite this, in enantioseparation science, these metallocenes were not comprehensively explored, and very few systematic analytical studies were reported in this field so far. In this context, our laboratories have started off systematic studies on the enantioseparation of planar chiral ferrocenes containing halogenated substituents and/or extended pai-electron clouds [2-4]. In particular, for compounds 1 and 2, the presence of extended pai-electron systems was shown to impact affinity of the most retained enantiomer toward amylose-based selectors by using polar organic solvents and aqueous-organic mixtures as mobile phases [2]. Moreover, the presence of the ferrocenyl framework proved to impact the enantioseparation of compound 3 compared to the analogue 4 [5]. In this poster presentation, the most recent observations of our laboratories in the enantioseparation of chiral compounds 1-4 on polysaccharide-based CSPs will be presented and discussed. [1]P. Peluso, V. Mamane. Ferrocene derivatives with planar chirality and their enantioseparation by liquid-phase techniques. Electrophoresis 43 (2022). DOI: 10.1002/elps.202200148. [2]A. Dessì, B. Sechi et al. Comparative enantioseparation of planar chiral ferrocenes on polysaccharide-based chiral stationary phases. Chirality 34 (2022) 609-619. [3]B. Sechi, A. Dessì et al. Unravelling functions of halogen substituents in the enantioseparation of halogenated planar chiral ferrocenes on polysaccharide-based chiral stationary phases: experimental and electrostatic potential analyses. J. Chromatogr. A 1673 (2022) 463097. [4] R. Dallocchio, A. Dessì, et al. Enantioseparation of planar chiral ferrocenes on cellulose-based chiral stationary phases: benzoate versus carbamate pendant groups. Electrophoresis 43 (2022). DOI: 10.1002/elps.202200205. [5]P. Peluso, V. Mamane et al. Optimization of the HPLC enantioseparation of 3,3'-dibromo-5,5'-disubstituted-4,4'-bipyridines using immobilized polysaccharide-based chiral stationary phases. J. Sep. Sci. 36 (2013) 2993-3003.