Structural Studies of Inclusion Complexes of HP-β-CD and Cetirizine by Combination of ROESY and Molecular Modelling Methods

Abstract

Cyclodextrin inclusion complexes (CD ICs) mimics the biological systems in molecular and chiral recognition mechanisms and therefore used as models in understanding molecular and chiral recognition because of their small size as compared to large biological systems. Cross peaks observed in the ROESY spectra of the mixture of cetirizine (CIT) and HP-β-CD demonstrate the portions of the guest encapsulated in the cavity that helped in establishing the probable orientations of complexes. Protons of both chlorobenzene and phenyl rings showed interactions with the cavity protons suggesting the formation of two complexes. Molecular mechanics (MM) and molecular dynamics (MD) studies were performed only from the wider end of the CD cavity because of steric hinderance of hydroxypropyl groups on the narrow side of CD cavity. Using the fusion of 2D ROESY and molecular modelling studies, the final structures of ensembles of the inclusion complexes were established.