Average orientation and location of benzyl alcohol-d(5) and alkyl benzyl-d(5) ethers in anionic nematic lyotropic liquid crystals

Abstract

Deuterium quadrupole splittings of benzyl alcohol-d(5) and a series of alkyl benzyl-d(5), ethers, with linear aliphatic chains from 1 to 12 carbon atoms, were measured using H-2 NMR spectroscopy. These molecules were dissolved in Nn anionic nematic lyotropic liquid crystals' prepared with sodium decyl sulfate (NaDS) and cesium decyl sulfate (CsDS). Using the quadrupole splittings, the two order parameters that completely describe the average orientation of the aromatic ring were calculated. From these values, we have inferred the mechanism of incorporation of the guest molecules into the superstructure of the aggregate. The effect of the added molecules on the integrity of the aggregate seems to depend on the electrostatic characteristics of the surface as well as the hydrophobic properties of the guest molecule. The quadrupole splittings suggest that benzyl alcohol is positioned near the interface, possibly hydrogen bonding with the interfacial water. This disrupts the integrity of the interface, particularly in the CsDS system with the more hydrophobic derivatives decreasing the mobility of the CsDS aggregate components.