Characterization of β-Cyclodextrin-Thymol Inclusion Complexes

Thymol had been confirmed to be applied to prevent the growth of bacteria and function as an antioxidant to maintain the quality of food products. It is known that a number of components of essential oils including thymol are suitable to form inclusion complexes with beta-Cyclodextrin, since they fit the hydrophobic cavity tightly. The beta-cyclodextrin-thymol(beta-CD-thymol) inclusion complexes were prepared by the saturated water solution method. SEM results showed that the lattice of beta-CD-thymol inclusions was different from hydrogen-bond-type crystal lattice of beta-CD and beta-CD-water inclusions; the disappearance of high-energy water molecules in the beta-CD cavity was observed from SAT data; the aromatic ring of the thymol was included in the beta-CD cavity, according to the FTIR data. Besides, according to the calculation of chemical structure, molecular size of thymol was estimated. These results supported a successful formation of the inclusion and the preliminary structure of host-guest inclusions was constructed, indicating the -CH3 is close to the beta-CD narrower rim, while the -CH2 and OH group is close to the wide one.