Synthesis and characterization of an amphiphilic cyclodextrin, a micelle with two recognition sites

OSCAR FERNANDO SILVA; MARIANA ADELA FERNÁNDEZ; SARAH PENNIE; ROBERTO GIL; RITA HOYOS DE ROSSI

LANGMUIR

Año: 2008 vol. 24 p. 3718 - 3726

0743-7463

A cyclodextrin derivative (Mod-CD) was synthetized through the monoesterification of b -cyclodextrin with 3-((E)-dec-2-enyl)-dihydrofuran-2,5-dione. The compound is an interesting surfactant which can form big aggregates not only through the interaction of the hydrophobic tails as in common amphiphilic compounds, but also through the inclusion of the alkenyl chain into the cavity of another Mod-CD molecule. The self inclusion of the chain in the cavity of cyclodextrin as well as the intermolecular inclusion was demonstrated by 1H NMR measurements which were able to detect methyl groups in three different environments. Besides, in the aggregates of Mod-CD, the cavity is available to interact with external guests such us phenolphthalein, 1-amine adamantane, and Prodan. Phenolphthalein have the same binding constant with Mod-CD and with b -CD but the equilibrium constant for the interaction with Prodan is about two times bigger for Mod-CD than with b -CD. This result is attributed to the fact that this probe interacts with the micelle in two binding sites: the cavity of the cyclodextrin and the apolar heart of the micelle as evidenced by the spectrofluorimetric behavior of Prodan in solutions containing different concentration of Mod-CD.