Solution inclusion complexes of cyclodextrins with sodium perfluorooctanoate

Abstract

Pre-micellar and micellar sodium perfluorooctanoate solutions (SPFO) were examined conductometrically with added α-cyclodextrin(α-CD), β-cyclodextrin (β-CD), and γ-cyclodextrin (γ-CD). The order of stability of the 1:1 inclusion complex was (β-CD > γ-CD > α-CD determined largely by the goodness of fit of the fluorocarbon chain in the CD cavity. Sodium ion electrode studies revealed that some Na + ion is associated with the (β-CD/SPFO complex. As shown by fluorine-19 nmr, (β-CD girds the SPFO molecule snugly amidship with the terminal CF 3 group still in solution. On the other hand, SPFO manages only a weak penetration of the fluorocarbon chain into the smaller α-CD cavity. Keywords: perflurooctanoate, cyclodextrin complexes, fluorocarbon surfactant, 19 F nmr.