Computational investigation of dimethoate and β-cyclodextrin inclusion complex: molecular structures, intermolecular interactions, and electronic analysis

The proposed study concerns the inclusion complexation of dimethoate (DMT) in the β-cyclodextrin (β-CD) molecule cage using a 1:1 stoichiometry. The interactions between DMT and β-CD were evaluated using PM7 and DFT in water and gas, using the CAMB3LYP functional 6-31G(d,p) basis set. All approaches agree with the optimal 3D structure, which includes full DMT inclusion in the β-CD cavity. Complexation, LUMO, and HOMO energies were computed. The natural bond orbital (NBO) and UV–visible calculations were determined and discussed. Additionally, the non-covalent intermolecular interactions between dimethoate and β-cyclodextrin are investigated through RDG, NCI, and IGM. The main forces stabilizing the examined inclusion complex are H-bond and van Der Waals interactions. Furthermore, the energy decomposition analysis (EDA) was applied highlighting the H-bonding by quantifying its strength. The TD-DFT method provided the electronic UV–vis spectra showing significant electronic transitions between the host and the guest by observing the molecular orbitals localizations.