13C‐CPMAS and 1H‐NMR Study of the Inclusion Complexes of β‐Cyclodextrin with Carvacrol, Thymol, and Eugenol Prepared in Supercritical Carbon Dioxide

Abstract

β-Cyclodextrin (β-CD) inclusion complexes with carvacrol (1), thymol (2), and eugenol (3) (components of essential oils of vegetable origin) were prepared by the supercritical CO₂ technique, and their structural characterization was achieved by means of ¹H-NMR in aqueous solution and ¹³C-CPMAS NMR in the solid state. Evidence of the formation of the inclusion complexes for all the examined systems was obtained by ¹H-NMR in solution, while 2D-ROESY-NMR experiments were used to investigate the geometry of inclusion. In addition, the dynamics of these inclusion complexes in the kHz timescale was investigated by analysis of the ¹H and ¹³C spin-lattice relaxation times in the rotating frame.