Chiroptical Phenomena in Reverse Micelles: The Case of (1R,2S)- Dodecyl (2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium Bromide (DMEB)

(1R,2S)-Dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB) aggregates dispersed in carbon tetrachloride have been investigated by Fourier transform infrared (FT-IR), vibrational circular dichroism (VCD) and 1H nuclear magnetic resonance (NMR) spectroscopy at various surfactant concentration and water-to-surfactant molar ratio. Experimental data indicate that, even at the lowest investigated concentration and in absence of added water, DMEBmolecules associate in supramolecular assemblies. At higherDMEBconcentration the aggregates
can confine watermolecules,making it plausible to think thatDMEB form reverse micelles and that watermolecules are quite uniformly distributed among them andmainly located in the proximity of surfactant head groups.Moreover, the water state in DMEB reverse micelles has been found to be different from that in pure water, due to system-specific water/surfactant head group interactions. 1H
NMR diffusion measurements of both water and DMEB emphasize their joined translational motion
characterized by a diffusion rate one order of magnitude lower than that of free molecules. Finally, VCD allowed us to show some characteristics of the association of optically active DMEB molecules
as reverse micelles and water confinement inside; namely, we monitored the vibrational optical activity of deuterated hydroxyl bonds of the self-assembled DMEB molecules and their interaction with D2Omolecules.