A SPECTRAL DISPLACEMENT STUDY OF THE BINDING CONSTANTS OF CYCLODEXTRIN-HYDROCARBON AND CYCLODEXTRIN-FLUOROCARBON SURFACTANT INCLUSION COMPLEXES

The spectral displacement technique with phenolphthalein as the chromo phore has been used to obtain 1:1 equilibrium binding constants (K-2) for a homologous series of hydrocarbon (he) (CnH2n+1COONa, n = 5-13) a nd fluorocarbon (fc) anionic surfactants (CnF2n+1COONa, n = 3-8) with beta-cyclodextrin (beta-CD). The magnitude of K-2 increases as the alk yl chain length increases in each homologous series. K-2 values in the ranges of 10(2)-10(5) M-1 and 10(1)-10(4) M-1 were obtained for the b eta-CD-fc and for the beta-CD-hc surfactant complexes, respectively. T he different binding affinity of beta-CD with he and fc surfactants is discussed in terms of such physicochemical properties of the guest sp ecies as hydrophobicity, geometrical size, conformational effects, mol ecular polarizability, and solvation of the head group.