首页|Unravelling functions of halogen substituents in the enantioseparation of halogenated planar chiral ferrocenes on polysaccharide-based chiral stationary phases: experimental and electrostatic potential analyses
Unravelling functions of halogen substituents in the enantioseparation of halogenated planar chiral ferrocenes on polysaccharide-based chiral stationary phases: experimental and electrostatic potential analyses
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NSTL
Elsevier
Planar chiral halogenated ferrocenes have come in useful as synthetic intermediates over the years, allowing for the preparation of functionalized derivatives for catalysis, material science, optoelectronics, and medicinal chemistry. Despite their chemical interest, few halogenated planar chiral ferrocenes have been prepared in enantiopure form by asymmetric synthesis so far. Enantioselective HPLC on polysaccharide-based chiral stationary phases (CSPs) has been used for resolving planar chiral ferrocenes making both enantiomers available. However, the enantioseparation of derivatives containing halogens or alkyl groups exclusively remains rather challenging. Given this context, in this study the enantioseparation of eleven dihalogenated planar chiral ferrocenes was systematically explored by using five polysaccharide-based CSPs under multimodal elution conditions. Baseline enantioseparations were achieved for nine analytes with separation factors (α) ranging from 1.15 to 1.66. Thermodynamic quantities associated with the enantioseparations were derived from van't Hoff plots, and for 1-halo-2-(iodoethynyl)ferrocenes (1-halogen = F, Cl, Br) halogen-dependent thermodynamic profiles were identified on a cellulose tris(3,5-dimethylphenylcarbamate)-based column. The impact of CSP structure and mobile phase (MP) polarity on the enantioseparation was evaluated. In addition, with the aim to unravel the functions of halogen substituents in mechanisms and noncovalent interactions underlying selector-selectand complex formation at molecular level, local electron charge density of specific molecular regions of the interacting partners were evaluated in terms of calculated electrostatic potential (V) and related source function (SF) contributions. On this basis, the impact of halogen type and position on the enantioseparation was investigated by correlating theoretical and experimental data.
Electrostatic potentialEnantioseparationHalogen bondPolysaccharide-based chiral stationary phasesSource function
Mamane V.、Pale P.、Sechi B.、Dessi A.、Dallocchio R.、Peluso P.、Gatti C.、Chankvetadze B.、Cossu S.
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Institut de Chimie de Strasbourg UMR CNRS 7177 Equipe LASYROC
Istituto di Chimica Biomolecolare ICB CNR Sede secondaria di Sassari
CNR-SCITEC Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”
Institute of Physical and Analytical Chemistry School of Exact and Natural Sciences Tbilisi State University
Dipartimento di Scienze Molecolari e Nanosistemi DSMN Università Ca' Foscari Venezia
NSTL
Elsevier
