Computer-aided molecular modeling study of enantioseparation of iodiconazole and structurally related triadimenol analogues by capillary electrophoresis: chiral recognition mechanism and mathematical model for predicting chiral separation.

Chiral separation of iodiconazole, a new antifungal drug, and 12 new structurally related triadimenol analogues had been developed by capillary electrophoresis (CE) using hydroxypropyl-γ-cyclodextrin (HP-γ-CD) as the chiral selector. The effect of structural features of analytes on Δt and R(s) was studied under the optimum separation conditions. Using molecular docking technique and binding energy calculations, the inclusion process between HP-γ-CD and enantiomers was investigated and chiral recognition mechanisms were discussed. The results suggest that hydrogen bonding between fluorine at position 4 of the phenyl group beside the chiral carbon and the hydroxyl group on the HP-γ-CD rim and face to face π-π interactions between two phenyl rings highly contributed to the enantiorecognition process between HP-γ-CD and iodiconazole. The N-methyl group beside chiral carbon also played an important role in enantiomeric separation. Additionally, the big difference in binding energy (ΔΔE) highly contributed to good separation in the presence of HP-γ-CD chiral selector, which may be a helpful initial guide for chiral selector selection and predicting the result of enantioseparation. Furthermore, the new mathematical equation established based on the results of molecular mechanics calculations exhibited good capability in predicting chiral separation of these triadimenol analogues using HP-γ-CD mediated CE.