NMR deuterium

Amphiphiles often have a complex phase behaviour with several liquid crystalline phases These liquid crystalline phases are often characterised by long-range order in one directior together with the formation of a layer structure. The molecules may nevertheless be able tc move laterally within the layer and perpendicular to the surface of the layer. Structura information can be obtained using spectroscopic techniques including X-ray and neutror diffraction and NMR. The quadrupolar splitting in the deuterium NMR spectrum can be... 

The summation runs over all carbon atoms in the chain. is the angle between the bilayei normal and the molecular axis, as discussed above. is the field strength this may be parametrised to reproduce appropriate experimental data such as the deuterium NMR order parameters or it may be obtained by a self-consistent protocol, as described below. In his work on lipid bilayers Marcelja used a slightly different expression for i jjisp which... 

Two physically reasonable but quite different models have been used to describe the internal motions of lipid molecules observed by neutron scattering. In the first the protons are assumed to undergo diffusion in a sphere [63]. The radius of the sphere is allowed to be different for different protons. Although the results do not seem to be sensitive to the details of the variation in the sphere radii, it is necessary to have a range of sphere volumes, with the largest volume for methylene groups near the ends of the hydrocarbon chains in the middle of the bilayer and the smallest for the methylenes at the tops of the chains, closest to the bilayer surface. This is consistent with the behavior of the carbon-deuterium order parameters,. S cd, measured by deuterium NMR ... 

We discuss the rotational dynamics of water molecules in terms of the time correlation functions, Ciit) = (P [cos 0 (it)]) (/ = 1, 2), where Pi is the /th Legendre polynomial, cos 0 (it) = U (0) U (it), u [, Is a unit vector along the water dipole (HOH bisector), and U2 is a unit vector along an OH bond. Infrared spectroscopy probes Ci(it), and deuterium NMR probes According to the Debye model (Brownian rotational motion), both... 

S Kdnig, W Pfeiffer, T Bayerl, D Richter, E Sackmann. I Phys II Erance 2 1589-1615, 1992. S Kdnig, TM Bayerl, G Coddens, D Richter, E Sackmann. Biophys I 69 1871-1880, 1995. S Kdnig. Untersuchungen zur Molekularen Bewegung und Diffusion von Membranen Mittles Inkoharenter, Quasielastischer Neutronenstreung und Deuterium-NMR. PhD Dissertation, TU Miinchen, Miinchen, 1993. 

Depolymerization mechanisms, 456 Depolymerized PET products, applications of, 531-532 Deuterium NMR, 328 Dexon, 28... 

H NMR spectroscopy studies of iron(IIl) a-alkyl and o-aryl porphyrins have been very important in elucidating spin states. Alkyl and most aryl complexes with simple porphyrin ligands (OEP, TPP, or TTP) are low spin, S — I /2 species. NMR spectra for the tetraarylporphyrin derivatives show upheld resonances for the porphyrin pyrrole protons (ca. — 18 to —35 ppm), and alternating upfield and downfield hyperfine shifts for the axial alkyl or aryl resonances. For -alkyl complexes, the a-protons show dramatic downfield shifts (to ca. 600 ppm), upfield shifts for the /3-protons (—25 to — 160 ppm) and downfield shifts for the y-protons (12 ppm). The cr-protons of alkyliron porphyrins are not usually detected as a result of their large downfield shift and broad resonance. These protons were first detected by deuterium NMR in the dcuterated complexes Fe(TPP)CD3 (532 ppm) and Fe(TPP)CD2CDi (562, -117 ppm). ... 

Deuterium NMR is used to study the molecular mobility of benzene-de in Na and Cs forms of zeolite X. The systems studied were prepared with loadings in the range 0.7 molecules/supercage to 5.6 and 5.0 mole-cules/supercage for (Na)X and (Cs,Na)X, respectively. 

Deuterium NMR has recently been used to study molecular motion of organic adsorbates on alumina (1.) and in framework aluminosilicates (2). The advantage of NMR is that the quadrupole interaction dominates the spectrum. This intramolecular interaction depends on the average ordering and dynamics of the individual molecules. In the present work we describe NMR measurements of deuterated benzene in (Na)X and (Cs,Na)X zeolite. 

Badia, A., Demers, L., Guccia, L., Morin, E. and Lennox, R.B. (1997) Structure and Dynamics in Alkanethiolate Monolayers Self-Assembled on Gold Nanoparticles A DSC, ET-IR, and Deuterium NMR Study. Journal of the American Chemical Society, 119, 2682-2692. 

Gourtieu, J. Deuterium NMR stereochemical analysis of threo-erythro isomers bearing remote stereogenic centres in racemic and non-racemic liquid crystalline solvents. Tetrahedron Asymmetry 2000, 11,1911-1918. 

Lindner, R., Bermann, E., and Gamamik, B. (1996). Characterisation of citrus honey by deuterium NMR. /. Agric. Food Chem. 44,139-140. 

In order to illustrate the potential applications of rheo-NMR five examples have been chosen. The first example deals with wormlike micelles [22] in which NMR velocim-etry is used to profile anomalous deformational flow and deuterium NMR spectroscopy is used to determine micellar ordering in the flow. The second example concerns flow in a soft glassy material comprising a solution of intermittently jammed star polymers [23], a system in which flow fluctuations are apparent. The third... 

The use of deuterium NMR methods holds promise for the investigation of a wide class of materials where shear deformation is likely to result in molecular ordering. 

Boulanger, Y. Schreier, S. Leitch, L. C. Smith, I. C. R, Multiple binding sites for local anesthetics in membranes Characterization of the sites and their equilibria by deuterium NMR of specifically deuterated procaine and tetracaine, Can. J. Biochem. 58, 986-995 (1980). 

These absorb at completely different frequencies, and since deuterium and proton chemical shifts are identical (also because deuterium is a spin-1 nucleus), deuterium NMR spectra are hardly ever measured. 

Hills, B.P. and Pardoe, K. 1995. Proton and deuterium NMR studies of the glass transition in a 10% water-maltose solution. J. Mol. Liquids 62, 229-237. 

Such order parameters can also be obtained from deuterium NMR measurements, and therefore one frequently finds predictions for these order parameters in the literature. The order parameter profile that belongs to the tails of the lipid membrane as given in Figure 5 is shown in Figure 6. 

Nuclear ion stopping, 74 433 Nuclear localization signal (NLS), 26 451 Nuclear magnetic resonance (nmr), 7 7 418 27 278. See also Deuterium nmr... 

A deuterium 2D Q-COSY experiment has recently been proposed,112 using a n/2 — t — n —12 pulse sequence (Fig. 8(a)), to study weakly oriented systems. The ID deuterium NMR spectrum obtained in a simple one-pulse experiment... 

The review aims to highlight some recent studies that involve liquid crystals and show the utility of newer pulse NMR techniques in LC. They may involve solutes dissolved in ordered phases and their applications, or may involve the molecular ordering, rotational and/or translational diffusion of solvent molecules. Deuterium NMR spectroscopy has demonstrated many advantages over other nuclei like H and 13C, but the need to specifically deuteriate mesogens is sometimes a major drawback. 13C NMR spectroscopy seems to be useful since non-enriched samples can often be used. However, the use of 13C NMR in semi-solids like LC often requires more sophisticated NMR techniques and instrumentation. There are indeed many uncharted... 

Deuterium nmr spectroscopy has been utilized for the last decade to determine large (primary deuterium) KIEs in reactions with isotopes present at the natural abundance level (Pascal et al., 1984,1986 Zhang, 1988). A great advantage of this approach is that labelled materials do not have to be synthesized. Neither is there any need for selective degradation procedures, which are often necessary to produce the molecules of low mass, e.g. C02, acceptable for isotope ratio mass spectrometry. Moreover, the KIEs for several positions can be determined from one sample. However, until quite recently the relatively low precision of the nmr integrations that are used for the quantitative assessment of the amount of deuterium at specific molecular sites has limited the applicability of this technique for determining small (secondary deuterium) KIEs. 

It has been postulated on the basis of the crystal structure of [Mn (tpp)(02 )], that the peroxide ligand in Fe(III)-peroxo porphyrin species is coordinated in a side-on bidentate manner (Scheme 2) (8). Interestingly, based on the deuterium NMR studies the [Mn tppXOa )] complex was characterized as the Mn(II)-superoxo species (55). This discrepancy has been explained by an alteration of the normal d orbital ordering, where the highest energy d orbital is a d 2- -02 hybrid not the (8). These examples show that... 

Deuterium NMR studies of chain and headgroup deuterated phospholipid bilayers and phospholipid—cholesterol mixtures... 

The solvent mobility in atactic polystyrene-toluene solutions has been studied as a function of temperature using NMR. The local reorientation of the solvent was studied using deuterium NMR relaxation times on the deuterated solvent. Longer range motions were also probed using the pulsed-gradient spin-echo NMR method for the measurement of diffusion coefficients on the protonated solvent. The measurements were taken above and below the gel transition temperatures reported by Tan et al. (Macromolecules, 1983. 16, 28). It was found that both the relaxation time measurements and the diffusion coefficients of the solvent varied smoothly through the reported transition temperature. Consequently, it appears that in this system, the solvent dynamics are unaffected by gel formation. This result is similar to that found in other chemically crossed-linked systems. 

The deuterium NMR spectra of toluene-d0 in aPS solutions consists of two resonances which are resolved and assigned to the methyl and aromatic groups. In these solutions spin-spin or dipolar couplings are small and consequently are not observed. As the temperature is lowered, the aromatic resonance systematically broadens while the methyl resonance remains relatively constant in width. The linewidths of the aromatic resonances are the same as those which would be predicted from the T2 measurements reported below. The separated resonances make it possible to determine the relaxation times of each type of resonance. 

This study is similar to those previously done by Derbyshire and Duff (20) and Nystrom et al. (21) who studied water swellable gels. However, in the first of these, the use of proton NMR complicated the relaxation data because of proton-proton coupling. Furthermore, their study focused on the freezing (or non-freezing) of water which also complicated matters. In the present study, we are always well above the freezing point of toluene so that one need not worry about the freezing of the solvent. The study by Nystrom et al. (21) used deuterium NMR of D2O, but an unusual temperature dependence was observed, possibly due to the exchange of the protons or deuterons. Our present data are not complicated... 

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