Nuclear magnetic resonance line shapes in lyotropic liquid crystals and related systems

Abstract

Nuclear spin relaxation in a hexagonal lyotropic liquid crystal J. Chem. Phys. 95, 6945 (1991); 10.1063/1.461506Nuclear magnetic resonance determination of the CF2 order parameter tensor in a lyotropic liquid crystal

Deuterium nuclear magnetic resonance investigation of the effects of proteins and polypeptides on hydrocarbon chain order in model membrane systems

“…2F). All samples were coarse dispersions in deuterium-depleted water, and all spectra were recorded at about 300C by using the quadrupole echo pulse sequence (4 (29,30 In the case of pure bilayers, the motional averaging of the 2H quadrupole splitting has been calculated explicitly (7,8,31). However, this cannot be done for the boundary layer lipid because details of its hydrocarbon chain configuration on the /rarnicidin B protein surface are unknown.…”

A Model for Magnetization Transfer in Tissues

“…The superLorentzian line shape was first observed in potassium laurate (21) and subsequently in lamellar liquid crystals (22) and lipids (23). It has also been seen as part of the complex proton NMR spectrum of whole cells (24).…”

NMR Studies of Membrane Structure and Dynamics

“…Both the Gaussian and superposition of Gaussian doublets resulted in reasonable agreement with experiment, while the superposition of Gaussians did not. By extending their analysis to the calculation of the shape of Jeener echoes (56), Bloom et al (55) showed that a superposition Gaussian doublets gave results more in accord with the observed FID than did the simple Gaussian. All of the above attempts at calculating.the lineshape in lyotropic systems suffer from the fact that the lineshape functions are unknown, and there is no reason a priori to assume that this shape is Gaussian.…”

“…Thus, the observed spectrum is a superposition of broadened Pake doublets (36) The results of Hagan et al also show that the early part of the FID is primarily sensitive to the wings of the broadened Pake doublet, while the central component contributes to the FID at longer times. Bloom and co-workers (55) showed that the FID exhibits a t-x dependence at long times. The results of Hagan et al confirm this dcpcndence, but the calculated magnitude of the t-1 component is smaller than is experimentally observed.…”

“…Chart et al (50) showed that these interpretations were incorrect and that the origin of the observed band shape is the incomplete averaging of static dipolar interactions present in the anisotropic phase. A number of attempts have been made to determine theoretical expressions for the complex lineshapes observed for amphiphilic molecules in the liquid crystalline state (14,18,(51)(52)(53)(54)(55). All of these treatments argue that, in addition to incomplete averaging of static dipolar interactions, effective axial symmetry about the bilayer normal is necessary for the observation of the super-Lorentzian band shape.…”