| Abstract
| - Conformational and orientational characteristics of amphiphiles incorporated in the hexagonal, lamellar,and reversed hexagonal aggregates formed by a ternary lyotropic system of sodium octanoate, 1-decanol,and water have been investigated. Deuterium NMR quadrupolar splittings observed from the randomlyand selectively deuterated compounds were simulated by a combined use of the rotational isomeric statescheme and the maximum entropy method. For the individual mesophases, the bond conformations andorientational order parameters of octanoate and 1-decanol were evaluated and related to the aggregatestructures. In the lamellar phase, in particular, the 1-decanol chain was found to exhibit peculiarconformations; the C−C bond nearest the OH group is fixed in the gauche state, the adjacent C−C bondalso shows a gauche preference, and the second C−C bond from the methyl terminal has a high gaucheprobability. It follows that the chain length of 1-decanol is almost equal to that of octanoate in the all-transconformation. Ab initio molecular orbital calculations at the MP2/6-31+G*//HF/6-31G* level for 1-butanolhave revealed the inherent conformational preference of the head portion of the alcohol chains; the firstC−C bond from the headgroup prefers the gauche state to the trans state by 0.27 kcal mol-1, and the g±g± states in the first and second C−C bonds from the OH group have a comparatively small free energyof 0.42 kcal mol-1 relative to the tt state.
|
