tA chalcogen bond (ChB) is a sigma-hole-based noncovalent interaction between a Lewis base and an elec-trophilic element of Group VI (O, S, Se, Te), which behaves as a Lewis acid. Recently, we demonstratedthat halogen bond, the more familiarsigma-hole-based interaction, is able to promote the enantioseparationof chiral compounds in HPLC environment. On this basis, an investigation to detect ChBs, functioningas stereoselective secondary interactions for HPLC enantioseparations, was started off and the resultsof this study are described herein. Our investigation also focused on the impact of the perfluorinatedaromatic ring as a pi greek-hole donor recognition site. For these purposes, seven atropisomeric fluorinated3-arylthio-4,4’-bipyridines were designed, synthesized and used as potential ChB donors (ChBDs) withtwo cellulose-based chiral stationary phases (CSPs) containing carbonyl groups as ChB acceptors (ChBAs).In addition, one and two analogues lacking fluorine and sulphur, respectively, were prepared as termsof comparison. The design of the test analytes was computationally guided. In this regard, electrostaticpotentials (EPs) associated with sigma - and pi greek-holes were computed and the atomic contributions to the sul-phur EP maxima were derived using a molecular space partitioning in terms of Bader’s atomic basins. Thisprocedure is akin to the Bader-Gatti electron density source function (SF) decomposition, yet suitablyextended to the EP field. For five 3-substituted-4,4’-bipyridines, thermodynamic parameters were derivedfrom van’t Hoff plots. Finally, the use of molecular dynamic (MD) simulation to model ChB in cellulose-analyte complexes was explored. Evidences that sigma -hole and pi greek -hole interactions can jointly drive HPLC enantioseparations through recognition sites generated by electronic charge depletion emerged fromboth experimental results and theoretical data.
|Titolo:||Enantioseparation of fluorinated 3-arylthio-4,4’-bipyridines: Insights into chalcogen and pi greek-hole bonds in high-performance liquid chromatography|
COSSU, Sergio Antonio [Funding Acquisition]
|Data di pubblicazione:||2018|
|Appare nelle tipologie:||2.1 Articolo su rivista |
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