Cycloheptaamylose–Barbiturate Inclusion Complexes: Solubility and Circular Dichroism Studies

The interaction of cycloheptaamylose with some barbiturates was examined by solubility analysis and by circular dichroism. Complexation by inclusion of the barbiturate within the cavity of cycloheptaamylose leads to: (a) an enhancement in the aqueous solubility of the barbiturate, and (b) extrinsic Cotton effects in the circular dichroism spectra. Measurements from both methods yield formation constants for the 1:1 interactions. The relative strength of interaction with cycloheptaamylose is of the following order: phenobarbital > pentobarbital > amobarbital > barbital.