The orientations of molecules dissolved in lyotropic surfactant solutions

Abstract

Nematic lyotropic liquid crystals prepared from sodium decylsulphate and from decylammonium chloride have been used as solvents for benzene and its monohalogenated derivatives. The results of an N.M.R. investigation of these compounds indicate that vibrational corrections to the ortho dipolar couplings are about 1·5 per cent and that the structure of fluorobenzene in lyotropic solution is different from the microwave structure. It was found that iodine had the major influence on the alignments of the molecules. Fluorine tended to align the C ₂ axis of the fluorobenzene molecule at 90° to that preferred by iodobenzene. This effect of substituent on the rotation by 90° decreased in the order I>Br>Cl>F. The preferential orientations were discussed in relation to the orientation of the superstructure of the nematic material. Only fluorobenzene orders, so that the carbon halogen bond is preferentially directed into the hydrocarbon water interface area and this significantly so only in the decylammonium phase.