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The structure and aggregation number of a discotic lyotropic liquid crystal, prepared from tetradecyltrimethylammonium chloride (TDTMACl)/decanol (DeOH)/NaCl/H2O, have been examined using fluorescence quenching of pyrene by hexadecylpyridinium chloride and molecular dynamics (MD). The fluorescence method gives an aggregation number of 258 ± 25 units (DeOH + TDTMACl). From the MD simulation, a lower limit for the aggregate dimension of 130 units of DeOH + TDTMACl is predicted. A stable oblate aggregate of 240 units was studied in detail. A strong polarization between the ammonium headgroups and chloride ions is observed from the calculated trajectory. DeOH headgroups are located, on average, 0.3 nm more to the interior of the aggregate than the TDTMACl headgroup and contribute to widening the interface by forming H-bonds with water. The radial distribution function of the ammonium headgroup shows that there are 16 water molecules in the first solvation sphere. The diagonal elements of the order parameter tensor of the tail atoms of both surfactants indicate that the interior of the micelle preserves about the same degree of order as at the interface, up to the last three atoms of the aliphatic chain, where the order starts to decrease.

Deuterium quadrupole splittings from two series of optical isomers, l- and d-N-acyl-1-phenyl-d5-2-aminopropane, with linear acyl chains ranging from 1 to 10 carbon atoms, were measured using ²H NMR spectroscopy. Both series of molecules were dissolved in anionic nematic cholesteric lyotropic liquid crystals prepared with cesium N-dodecanoyl-l-alaninate. With these values, the two order parameters that completely characterize the average alignment of the aromatic ring were calculated. Differential incorporation of both series of isomers into the aggregate is observed for intermediate size molecules, as evidenced by the values of the order parameters of the ring. Our results indicate that the first two derivatives in both series, l- and d-C1 and l- and d-C2, are located near the interface, possibly forming a H bond between the NH and/or CO groups and the interstitial water molecules. Increasing the hydrophobicity of the chain by adding one carbon atom induces a decrease in the overall alignment. Intermediate acyl chain length molecules progressively incorporate sufficiently into the aggregate for both asymmetric carbons, from the surface and the guest molecule, to approach each other, introducing differences in the average alignment of the aromatic ring between both series of isomers. Longer acyl chain derivatives incorporate deeper into the micelle and do not show this differentiation, possibly because the asymmetric carbons are located far away from each other.