Influence of morphology on polar solvation dynamics in lecithin reverse micelles

The continuous nonpolar phase can change the morphology of lecithin reverse micelles dramatically. In alkane solvents, increasing the hydration leads to gelation as isolated water droplets transform into an entangled tube net work. In contrast, increasing the hydration for lecithin in benzene maintai ns isolated, largely spherical traditional reverse micelles. Solvation dyna mics experiments have been carried out in the two different micellar enviro nments. These measurements show that solvation dynamics are considerably mo re restricted in the tubular micelles than in the spherical droplets. This is interpreted as evidence fur water pool formation and disorder at the int erface in the spherical micelles and supports the hypothesis of substantial water incorporation into the tubular micelles. To perform solvation dynami cs experiments in the benzene/lecithin/water reverse micelles, we have synt hesized a new headgroup-labeled probe molecule. This synthesis, coupling th e standard solvation dynamics probe, coumarin 343, to phosphatidylethanolam ine through an amide bond, is presented.