Inclusion phenomena of clove oil with α-, β-, γ- and heptakis (2,6-di-O-methyl)-β-cyclodextrin

Inclusion interactions of -, -, - and heptakis (2,6-di-O-methyl)--cyclodextrin (DM-CD) as hosts with clove oil (an impure eugenol, I-Eug) as guest in aqueous solution were investigated by fluorescence emission spectra. The binding constants of different hosts to I-Eug in aqueous solution decreased in the order: - - DM- -CD. Two solid supramolecular inclusion complexes, I-Eug--CD and I-Eug--CD, were prepared and characterised by nuclear magnetic resonance, powder X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. All the results proved the formation of I-Eug-CD. The inclusion differences between I-Eug and pure eugenol were discussed. The relative contents of the main component eugenol (Eug), second component (eugenol acetate, Eua) and others in I-Eug were found to be fairly different before and after being included by -CD, according to the data obtained from high performance liquid chromatography. This could be a practical method to extract the effective components (Eug and Eua) from I-Eug.