Complexation between α-cyclodextrin (α-CD) and aliphatic amines in water and DMF solvents was studied by calorimetry. Amines form complexes with α-CD in both solvents but the nature of the complexes is quite different. In DMF the amines donate a hydrogen from the amine N-H group to the cyclodextrin forming a normal hydrogen bonded complex. In DMF solutions with large amine concentrations, complexes other than 1:1 are observed. In contrast, in aqueous environment the amines form inclusion complexes in which the amine alkyl group penetrates the α-CD cavity and is stabilized by van der Waals interactions. The equilibrium constants for the complexes formed in water solvent increase with increasing alkyl chain length due to an entropy effect.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Physical and Theoretical Chemistry