Theoretical study of the inclusion processes of Venlafaxine with β-cyclodextrin

Geometry optimizations of Venlafaxine/β-Cyclodextrin complex were carried out using MM2, PM3, ONIOM2 and ONIOM3 methods. The binding and complexation energies for both orientations considered in this research are reported. The geometry of the most stable complex shows that the aromatic ring is deeply self-included inside the hydrophobic cavity of β-CD also an intermolecular hydrogen bond is established between host and guest molecules. This suggests that hydrophobic effect and hydrogen bond play an important role in the complexation process. Additional information about binding in the complexes (C1) and (D1) was obtained by NBO analysis, the stabilization energy E(2) calculated with ONIOM3 method is more significant.