ReviewComputational approach in the study of the inclusion processes of Thymol with β-cyclodextrin

- Two orientations jof Thym/β-CD were investigated.
- Both Thym and β-CD were deformed after complex formation.
- TD-DFT and NBO calculations suggest a transfer of charge between β-CD and Thym.
- From MEP electrons density is mostly localized on oxygen atoms of β-CD.

This study presents a computational investigation of inclusion complex formation between thymol (Thym) and β-cyclodextrin in vacuum. Geometry optimizations were performed by HF/6-31G(d,p), B3LYP/6-31G(d,p), PBEPBE/6-31G and CAM-B3LYP/6-31G levels of theory. Time-dependent density functional theory (TD-DFT) was used to calculate the electronic transitions of formed complexes at B3LYP/6-31G(d,p) level using the ground state geometry from optimized complexes in A and B orientations. Ecomplexation, Edeformation, Einteraction have been calculated and compared for both orientation A and B. PBEPBE/6-31G and CAM-B3LYP/6-31G calculations shows that B orientation is more stable than A one, for each orientation Thym is totally encapsulated into β-CD cavity. Charge transfer between host and guest is the most important factor stabilizing the inclusion complex Thym/β-CD; this is confirmed by TD-DFT calculation and NBO analysis.