CYCLOPENTANOL-ENHANCED SOLUBILIZATION OF POLYCYCLIC AROMATIC-HYDROCARBONS BY CYCLODEXTRINS

The effect of cyctopentanol on the solubilization of six polycyclic aromatic hydrocarbons (PAHs) by beta-cyclodextrin (beta-CD) and gamma-cyclodextrin (gamma-CD) is reported in this paper. The addition of 0.1% v/v cyclopentanol significantly enhances the solubilization power of beta-CD for pyrene, acenaphthene, phenanthrene, and fluoranthene, which form 1:2 complexes with beta-CD. However, the solubilization of acenaphthene and phenanthrene by beta-CD in the presence of cyclopentanol decreases at higher beta-CD concentrations following an initial increase. This phenomenon is attributed to the cyclopentanol-induced formation of insoluble beta-CD aggregates. In contrast, cyclopentanol produces no pronounced effect and a marked decrease in the solubilization power of beta-CD for naphthalene and anthracene, respectively These two compounds form 1:1 complexes with beta-CD. The solubilization of all six PAHs by gamma-CD is significantly enhanced by 1% v/v cyclopentanol. This result indicates that the addition of cyclopentanol increases the ''hydrophobicity'' of the gamma-CD cavity and increases the solubilization power of gamma-CD without inducing structure-dependent selectivity. On the basis of linearity and nonlinearity observed in the solubilization curves of the six PAHs in the presence of cyclopentanol, it is suggested that naphthalene, anthracene, acenaphthene, and phenanthrene form 1:1 complexes with gamma-CD while fluoranthene and pyrene form both 1:1 and 2:2 complexes.