The confinement of D and L dimethyl tartrate in lecithin reverse micelles dispersed in cyclohexane has beeninvestigated by FT-IR, polarimetry, electronic and vibrational circular dichroism (ECD and VCD), 1H NMR,and small-angle X-ray scattering (SAXS). Measurements have been performed at room temperature as afunction of the solubilizate-to-surfactant molar ratio (R) at fixed lecithin concentration. The analysis ofexperimental data indicates that the dimethyl tartrate molecules are solubilized within reverse micelles inproximity to the surfactant head groups in the same way for the D and L forms. The encapsulation of dimethyltatrate within lecithin reverse micelles involves changes in its H-bonds, from what is observed in the puresolid or in CCl4 solutions; this is a consequence of the establishment of specific solute-surfactant headgroupinteractions and of confinement effects. In the 0 e R e 1.7 range, SAXS profiles of dimethyl tartrate/lecithin/cyclohexane micellar solutions are well-described by a model of interacting polydisperse spherical micellarcores whose mean radius does not change appreciably with R (i.e., it changes from about 18 to 20 Å). 1HNMR diffusion measurements of both dimethyl tartrates and lecithin were rationalized in terms of collectivetranslational motions of the entire micellar aggregate and of their molecular diffusion among clusters ofreverse micelles. The association of optically active lecithin with D and L dimethyl tartrate leads to the formationof self-organized supramolecular aggregates whose interesting chiroptical features are evidenced by polarimetryand CD.
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry