Magnetic resonance in liquid crystals

See, for example, Emsley JW (ed) (1985) Nuclear magnetic resonance in liquid crystals. Reidel, Dordrecht... 

C. P. Slichter. Nuclear Magnetic Resonance in Liquid Crystals, ed., by J. W. Emsley, Riedel, Dordrecht, 1985. 

For leading references on NMR in liquid crystalline solvents see (a) J. W. Emsley and J. C. Lindon, NMR Spectroscopy Using Liquid Crystal Solvents, Pergamon Press, Oxford, UK, 1975 (b) J. W. Emsley, ed., Nuclear Magnetic Resonance of Liquid Crystals, D. Riedel Publishing Co., Dordrecht, The Netherlands, 1985 (c) E. E. Burnell and C. A. de Lange, eds., NMR of Orientationally Ordered Liquids, Kluwer Academic Press, Dordrecht, The Netherlands, 2003. 

Emsley, J. W., Measurement of orientational ordering by NMR, in Nuclear Magnetic Resonance of Liquid Crystals, Reidel, D., Ed. Dordrecht, The Netherlands, 1985. 

M. Vilfan, N. Vrbancic-Kopac Nuclear magnetic resonance of liquid crystals with an embedded polymer network. In Liquid Crystals in Complex Geometries, ed by G.P. Crawford, S. Zumer (Taylor Ftancis, London 1996) chap 7. 

Emsley JW (1985) Measurement of orientational ordering by NMR. In Emsley JW (ed) Nuclear magnetic resonance of liquid crystals. D Reidel, Dordrecht, pp 379—412... 

C. Zannoni [ in Nuclear Magnetic Resonance of Liquid Crystals Ed. J.W. Emsley (Reidel, 1985) ch.l ]... 

Of spectroscopic teclmiques, nuclear magnetic resonance (NMR) has been most widely used to measure orientational ordering in liquid crystals [M, 57 and ]. Most commonly, changes of line splittings in the spectra of... 

It is useful to describe the amount of orienlalional order wilh a single quantity. X-ray. uv. optical, ir, and magnetic resonance techniques are used to measure ihe order parameter in liquid crystals. 

Nuclear magnetic resonance has been shown to be a most effective method for the study of lipid chemistry (Chapman, 1965 1972 Henrikson, 1971). With the advent of commercially available fast Fourier transform spectrometers, high resolution natural abundance 1 3 C spectra and relaxation times of lipids have become relatively commonplace. Utilization of these 1 3C nmr techniques has yielded a considerable amount of information concerning the mobility and organization of lipids in liquid crystals and membranes (Oldfield and Chapman, 1971). 13C Chemical shifts of lipids are given in Table 21. The rest of this discussion will be devoted to the interpretation of these results. 

In liquid crystals the proton resonance line width and the related effective transverse spin relaxation time T2 depend on the angle 9 between the magnetic field and the director n, which is described approximately... 

W.J. Emdey, Liquid Crystals general considerations. Encyclopedia of Nuclear Magnetic Resonance, in D.M. Grant, R.K. Harris (Eds.), vol. 4, John Whey Sons, Chichester, UK, 1996, p. 2788. 

Broad-line proton magnetic resonance of polymer crystals in the presence of a nonprotonated liquid has been used to determine the surface fraction for TPBD and poly(-4-methylpentene-l). Some results obtained using this method on TPBD crystals are included in Table V the surface fraction obtained by broad-line nmr is in close agreement with those from epoxidation and bromination. 

Johansson, A. Lindman, B. In Liquid Crystals and Plastic Crystals, Nuclear Magnetic Resonance Spectroscopy of Liquid Crystals-Amphiphilic Systems, G.W. Gray and P. A. Winsor, eds. Ellis Horwood Publishers, Chichester, 1974, Vol. 2, pp. 192-230. 

Nuclear magnetic resonance (NMR), in particular, deuterium NMR, has proven to be a valuable technique for determining the nature of molecular organization in liquid crystals. The utility of the NMR technique derives from the fact that the relevant NMR interactions are entirely intramolecular, i.e. the dominant interaction is that between the nuclear quadrupole moment of the deuteron and the local electric-field gradient (EFG) at the deuterium nucleus. The EFG tensor is a traceless, axially symmetric, second-rank tensor with its principal component along the C—D bond. In a nematic fluid rapid anisotropic reorientation incompletely averages the quadrupolar interaction tensor q, resulting in a nonzero projection similar to the result in Eq. (5.6) ... 

There are a large number of studies concerned with nuclear spin relaxation [7.45] in liquid crystals. The majority of these involve observation of the total proton magnetization arising from all protons in a mesogen. The experiments usually yield only one relaxation time, which is difficult, if not impossible, to relate to details of motion in the liquid crystalline phase. Deuteron and carbon-13 NMR may be used to study nuclear spin relaxation at several sites in a mesogen. In particular, direct measurement of spectral densities using deuterium resonant lines has made testing of motional models possible in liquid crystals. As yet, there is no report on systematic comparison between the different models of molecular reorientation. 

---