Chiral recognition of propranolol enantiomers by chiral ionic liquid: A quantum chemical calculation analysis

摘要

Electronic structure and noncovalent interactions of the complexes of 1-butyl-3-methylimidazolium (T-4)-bis[(alpha S)-alpha-(hydroxy-O)benzeneacetato-kappa O] borate ionic liquid (IL) with propranolol hydrochloride enantiomers are analyzed using hybrid M06-2X density functional theory. Based on the binding energies, the S-Propranolol/IL (S-Pr/IL) complex is more stable than the R-Propranolol/IL (R-Pr/IL), which is in accordance with the experimental results (Absalan et al., 2012). Reduced density gradient (RDG) method, natural bond orbital (NBO) and electrostatic potential (ESP) analysis show that the intermolecular interactions in S-Pr/IL system are stronger than those in R-Pr/IL. Results of Atom in molecule (AIM) analysis indicate that two strong H-bonds and also weak pi-stacking interactions are the main reason of the stability of S-Pr/IL complex. Moreover, the anion found to contribute mainly in forming the strong H-bonds and weak Van der Waals interactions with propranolol enantiomers in both studied complexes.