Theoretical study of the inclusion processes of ibuprofen enantiomers with native and modified β-CDs

PM3 calculations in vacuum were performed on the inclusion complexation of beta-cyclodextrin (beta-CD), heptakis-(2-O- methyl)-beta-cyclodextrin (2-Me-beta-CD) and heptakis-(6-O-methyl)-beta-cyclodextrin (6-Me-beta-CD) with ibuprofen (IB) enantiomers. Inclusion process pathways are described and the most probable structure of the 1: 1 complex are sought through a potential energy scan. The energy differences between the inclusion complexes and the hosts ( native and modified CDs) by calculation show that modified CDs have much more interaction sites with IB and enhance van der Waals interaction and hydrophobic interaction between them, form more stable complexes than native CD does. Stabilization energies of S-IB complexes are higher than that of R-IB complexes both for native and modified CDs.