Computational study of inclusion complex between Omeprazole enantiomer and β-Cyclodextrin: NBO and RDG analysis

In this study, it has been done NBO and RDG analysis of the R/S-Omeprazole and beta-Cyclodextrin inclusion complexes by using density functional theory computational method, one-point calculation with the exchange-correlation functional of B3LYP and basis set of 6-31g (d). The results of the NBO analysis show that there are 7, 52, 5, and 44 of hydrogen bonds in the inclusion complex of beta-Cyclodextrin and R-Omeprazole (1: 1), beta-Cyclodextrin and R-Omeprazole (2: 1), beta-Cyclodextrin and S-Omeprazole (1: 1), and beta-Cyclodextrin and S-Omeprazole (2: 1), respectively. The results of the RDG analysis confirm that the R/S-Omeprazole inclusion complex with beta-Cyclodextrin formed a Van der Waals interaction and also the effect of other than hydrogen bonds. However, the steric effect can be ignored because the amount is relatively small compared to hydrogen bonds and the Van der Waals interactions.