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Chiroptical Phenomena in Reverse Micelles: The Case of (1 R ,2 S )‐Dodecyl (2‐hydroxy‐1‐methyl‐2‐phenylethyl)dimethylammonium Bromide (DMEB)
Author(s) -
Abbate Sergio,
Passarello Marco,
Lebon France,
Longhi Giovanna,
Ruggirello Angela,
Turco Liveri Vincenzo,
Viani Fiorenza,
Castiglione Franca,
Mendola Daniele,
Mele Andrea
Publication year - 2014
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.22309
Subject(s) - chemistry , micelle , molecule , bromide , pulmonary surfactant , diffusion , circular dichroism , analytical chemistry (journal) , crystallography , organic chemistry , aqueous solution , biochemistry , physics , thermodynamics
ABSTRACT (1 R ,2 S )‐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 1 H 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, DMEB molecules associate in supramolecular assemblies. At higher DMEB concentration the aggregates can confine water molecules, making it plausible to think that DMEB form reverse micelles and that water molecules are quite uniformly distributed among them and mainly 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. 1 H 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 D 2 O molecules. Chirality 26:532–538, 2014. © 2014 Wiley Periodicals, Inc.