Structural and energetic investigation on the host/guest inclusion process of benzyl isothiocyanate into β-cyclodextrin using dispersion-corrected DFT calculations.

The formation of host-guest complex between benzyl isothiocyanate (BITC) and β-cyclodextrin (β-CD) was studied using dispersion-corrected density functional theory calculations. The complexation process was monitored using molecular docking simulations, natural bond orbital (NBO) technique, nuclear magnetic resonance (1H NMR) chemical shift calculations and non-covalent interactions (NCI) analysis. All these approaches are consistent with experimental findings. The calculated complexation energy was negative indicating the formation of inclusion complex. The most stable complexation of BITC involves the inclusion of its aromatic moiety in β-CD cavity (model A) in accord with experimental NMR chemical shift data. The non-covalent interactions (NCI) based on the reduced density gradient (RDG) analysis reveal that mainly weak Van der Waals intermolecular interactions between BITC and β-CD provide and ensure stability for the complexation process.