Quantitative conformational stability host-guest complex of Carvacrol and Thymol with β-cyclodextrin: a theoretical investigation

Abstract

In this research paper, we describe a study on the inclusion complex formation between both of the most important antioxidants Carvacrol, Thymol and beta-cyclodextrin ( $$\beta-CD$$ ). We use docking and quantum chemical calculations to ascertain the capability of the nano hydrophobic cavity of beta-cyclodextrin ( $$\beta-CD$$ ) to encapsulate Carvacrol and Thymol compounds (X), the formation of 1:1 a stoichiometry ratio of host-guest inclusion complex ( $$X@\beta-CD$$ ) in the gas and solution phase using different quantum mechanical methods including semi-empirical (PM6), ab initio (HF), and density functional theory (B3LYP), all HF and DFT calculations have been performed with the 6-31G and 6-31+G(d) basis sets. Two modes of complexation were taken into consideration ‘orientation’. The results obtained with B3LYP/6-31+G(d) method clearly indicate that the complexes formed are energetically favored with or without solvent. Two groups of conformers were found.