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.

Unravelling functions of halogen substituents in the enantioseparation of halogenated planar chiral ferrocenes on polysaccharide-based chiral stationary phases: experimental and electrostatic potential analyses

Cossu S.;
2022-01-01

Abstract

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.
File in questo prodotto:
File Dimensione Formato  
2022 JCA Ferroceni 1-s2.0-S0021967322002904-main.pdf

non disponibili

Descrizione: Articolo Principale
Tipologia: Documento in Post-print
Licenza: Accesso chiuso-personale
Dimensione 2.68 MB
Formato Adobe PDF
2.68 MB Adobe PDF   Visualizza/Apri

I documenti in ARCA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10278/3758527
Citazioni
  • ???jsp.display-item.citation.pmc??? 1
  • Scopus 6
  • ???jsp.display-item.citation.isi??? 5
social impact