Inclusion complexes of cyclodextrins with cinnamic acid derivatives: Dissolution and thermal behavior.

Typical Bs type phase solubility diagrams were obtained for α-and β-cyclodextrins (α-CyD and β-CyD) with methyl cinnamate, ethyl cinnamate, and cinnamaldehyde in water at 25°. Solid complexes for α-and β-CyDs with three guest molecules were obtained and their molar ratios were found to be 2 : 1 (α-CyD/guest molecule) and 1 : 1 (β-CyD/guest molecule), respectively. In sharp contrast, apparent stability constant (Kc') and dissolution rate (kc') of α-CyD complexes were larger than those of β-CyD complexes. The thermal gravimetric analysis thermogram showed that the volatility of the guest molecule was lowered by the formation of CyD inclusion complex.