Suppression of Residual Hydrophobicity of Amphiphilic Amino Acids by forming Association Complexes with β-Cyclodextrin

Department of Chemistry, University of Delhi, Delhi-11 0 007

Manuscript received 21 January 1994,revised 28 June 1994, accepted 23 February 1995

The interfacial tension at the benzene/water interface has been studied in the presence of four amphiphilic amino acids, viz. alanine,
phenylalanine, valine and leucine in presence and in absence of ß-cyclodextrin. The interfacial tension which is otherwise decreased with the increased concentration of amino acids, was found to increase gradually with progressive addition of cyclodextrin. The results have been explained on the basis of inclusion complexation between the hydrocarbon side-chain of the amino acid and cyclodextrin. The formation constants and other thermodynamic parameters have been evaluated for the inclusion complexes. It has been concluded that long and straight hydrocarbon side-chains are preferably included into the cavity of cyclodextrin molecule.