title: Insights into halogen bond-driven enantioseparations.
abstract: Although the halogen bond (XB) has been so far mainly studied in silico and in the solid state, its potential impact in solution is yet to be fully understood. In this study, we describe the first systematic investigation on the halogen bond in solvated environment by high-performance liquid chromatography (HPLC). Thirty three atropisomeric polyhalogenated-4,4'-bipyridines (HBipys), containing Cl, Br and I as substituents, were selected and used as potential XB donors (XBDs) on two cellulose-based chiral stationary phases (CSPs) containing potential XB acceptors (XBAs). The impact of the halogens on the enantiodiscrimination mechanism was investigated and iodine showed a pivotal role on the enantioseparation in non-polar medium. Electrostatic potentials (EPs) were computed to understand the electrostatic component of CSP-analyte interaction. Moreover, van't Hoff studies for ten HBipys were performed and the thermodynamic parameters governing the halogen-dependent enantioseparations are discussed. Finally, a molecular dynamic (MD) simulation is proposed to model halogen bond in polysaccharide-analyte complexes by inclusion of a charged extra point to represent the positive 'σ-hole' on the halogen atom. On the basis of both experimental results and theoretical data, we have profiled the halogen bond as a chemo-, regio-, site- and stereoselective interaction which can work in HPLC environment besides other known interactions based on the complementarity between selector and selectand.
authors.affiliation: Istituto di Chimica Biomolecolare ICB, CNR, UOS di Sassari, Traversa La Crucca 3, Regione Baldinca, I-07100 Li Punti, Sassari, Italy. Electronic address: p.peluso@icb.cnr.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Peluso
authors.affiliation: Institut de Chimie de Strasbourg, UMR 7177, Equipe LASYROC, 1 rue Blaise Pascal, BP 296 R8, 67008 Strasbourg Cedex, France. Electronic address: vmamane@unistra.fr.
authors.forename: Victor
authors.initials: V
authors.lastname: Mamane
authors.affiliation: Cristallographie, Résonance Magnétique et Modélisations (CRM2), UMR CNRS 7036, Université de Lorraine, BP 70239, Bd des Aiguillettes, 54506 Vandoeuvre-les-Nancy, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Aubert
authors.affiliation: Istituto di Chimica Biomolecolare ICB, CNR, UOS di Sassari, Traversa La Crucca 3, Regione Baldinca, I-07100 Li Punti, Sassari, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Dessì
authors.affiliation: Istituto di Chimica Biomolecolare ICB, CNR, UOS di Sassari, Traversa La Crucca 3, Regione Baldinca, I-07100 Li Punti, Sassari, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Dallocchio
authors.affiliation: ISPA, CNR, UOS di Sassari, Traversa La Crucca 3, Regione Baldinca, I-07100 Li Punti, Sassari, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Dore
authors.affiliation: Institut de Chimie de Strasbourg, UMR 7177, Equipe LASYROC, 1 rue Blaise Pascal, BP 296 R8, 67008 Strasbourg Cedex, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Pale
authors.affiliation: Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari di Venezia, Via Torino 155, I-30172 Mestre Venezia, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Cossu
mesh_terms: D002482:Cellulose / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D006219:Halogens / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D006219:Halogens; D011134:Polysaccharides; D002482:Cellulose
keywords: Atropisomers; Bipyridines; Chiral recognition; Electrostatic potential surfaces; Halogen bond; Polysaccharide-based chiral stationary phases