By C. L. / Kungwar, A. C. / Tracey, A. S. / Diehl, P. Khetrapal
1. Lyotropic Liquid Crystals the category of compounds often called thermotropic liquid crystals has been extensively used in easy study and in the course of contemporary years. The homes of those fabrics are such that on heating from the forged to the isotropic liquid country, part transitions take place with the formation of 1 or extra intermediate anisotropic drinks. the original and infrequently startling houses of those liquid crystals are the homes of natural compounds. even if, there exists a moment classification of gear referred to as lyotropic liquid crystals which receive their anisotropic houses from the blending of 2 or extra elements. one of many elements is amphiphilic, containing a polar head staff (generally ionic or zwitterionic) connected to at least one or extra long-chain hydrocarbons; the second one part is mostly water. Lyotropic liquid crystals take place abundantly in nature, relatively in all dwelling structures. to that end, a brilliant destiny turns out guaranteed for reviews on such platforms. Even now, a few of the houses of those structures are poorly understood. it's the function of this evaluation to consolidate the consequences bought from nuclear magnetic resonance stories of such platforms and to supply a coherent photo of the sphere. the most common instance of a lyotropic liquid crystal is cleaning soap in water. a typical cleaning soap is sodium dodecylsulphate the place an ionic team (sulphate) is hooked up to a hydrocarbon chain containing twelve carbons.
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8 kcallmole r81, 891 Diffusion coefficient studies have been made of lecithin in various solvents like n-hexane, n-decane and methanol and the potassium octadecanoate-water system [345]. Although the diffusion coefficients of lecithin itself could not be obtained, the effect of lecithin on the coefficients of the various solvents was readily detected. Results on the lecithin-n-hexane system are shown in Fig. to. 2 x to- 5 cm2 / sec) initially starts to fall rapidly on addition of lecithin. However, around 6 % concentration of the lecithin, the diffusion coefficient starts to increase, reaching a maximum around 10% concentration of the lecithin; with further solute, the diffusion coefficient decreases, reaching a plateau around 14 to 20 % concentration.
Am. Chern. Soc. 96, 1198 (1974) with permission of the copyright owners and the authors. Copyright by the American Chemical Society 15 variable amounts of water to the polypeptide solution, thus yielding several sets of S values and quadrupole splittings. Three simultaneous equations involving different S values were solved to yield the complete quadrupole coupling tensor in the molecular axis system. The results were then checked from a fourth orientation. d) Structure of Ions. Nuclear magnetic resonance spectra from ions in lyotropic liquid crystals provide the only means of determining structures of ions in other than the solid state.
TJ1~t ~ .. ~; ............... ~ Fig. II. 13C-Fourier transform NMR spectra of the n-decylammonium ion (CF3 COO- salt in D 2 0). The peak assignments correspond to the numbering of the carbons starting from the head group. The lower spectrum (B) was obtained from an anisotropic phase at 36°. The upper spectrum (A) was from the same solution at 39°, at which temperature the isotropic micellar phase is stable. [Reprinted from the 1. Am. Chern. Soc. 96, 5456 (1974) with permission of the copyright owner and the authors.