2H-NMR spectroscopy

Reduction of both nickel porphyrins and thiaporphyrins to Ni1 species has been studied by EPR and 2H NMR spectroscopy.179, 2 58 The Ni1 complex of 5,10,15,20-tetraphenyl-21-thiaporphyrin has been isolated and characterized. Reaction of this complex with sulfur dioxide produced a paramagnetic five-coordinated Ni1 S02 adduct, while reaction with nitrogenous base ligands (amines, pyridines, imidazoles) yielded five- and six-coordinate complexes. In addition, the crystal structure of Ni1 diphenyldi-p-tolyl-21-thiaporphyrin has been determined. The coordination geometry about the nickel center is essentially square planar with extremely short Ni—N and Ni—S bonds (Ni—N = 2.015(2) A, 2.014(12) A, and 1.910(14) A and Ni—S = 2.143(6) A).2359... 

Figure 6. V ariation of the orientational order parameter 5 along the hydrocarbon chains of the lipids of DMPC lipid bilayers, according to MD simulations of Berger et al. [58]. The line is drawn to guide the eye. The spheres are experimental values obtained by Seelig and Seelig [59] using 2H-NMR spectroscopy. (Numbering of C-atoms from the head group to the CH3 terminal group). Redrawn from [58] by permission of the Biophysical Society...

This conclusion is in accord with the results of MINDO/3 quantum-chemical calculations. Cation 7 is also prone to undergo a rather slow degenerate rearrangement by 1,2-bridge shift (AG is about 60 kJ/mol) (Scheme 8). This rearrangement was probed via 2H NMR spectroscopy, when the 9-CD3-analog of carbinol 5 was used as precursor for carbocation generation. At -50 °C cations 6-8 transform firstly into l,l,2,3,3a,4,8b-heptamethyl-l,3a,8b-trihydrobenzopentalenium ion (9) and then (partially) into 1,1,2,3,4,4,8b-heptamethyl-l,4,8b-trihydrobenzopentalenium ion (10) (Scheme 9). 

For /er/-butyl alcohol, we have observed (8f) with l3C CP/MAS and 2H NMR spectroscopy, the formation of tert-butyl silyl ether (TBSE) at temperatures as low as 296 K. In these experiments,, 3C and 2H-labeled tert-butyl alcohols were used ... 

In chromium(III) complexes, proton hyperfine shifted signals are expected to be broad beyond detection. Actually, the binding of Cr(III) is followed in proteins by the disappearance of signals [127-129]. 2H NMR spectroscopy can be used in the study of small chromium(III) complexes to reduce the line broadening. 

Incubation with (2 RS,3R)-[3-2H]lysine and with (2RS,3S)-[3-2H]lysine, respectively, and subsequent 2H NMR spectroscopy of the isolated /Mysine proved that the pro-3 R hydrogen of a-lysine 24 is transferred to the pro-2 R position in 25 whereas the pro-3S hydrogen is retained at C3 (Scheme 1.6.6). 

Several studies have been performed to analyze the effect of membrane composition on accumulation and transport of antineoplastic drugs. In particular, the role of anionic lipids in transport and passive diffusion, as well as on the binding of doxorubicin and its effect on the degree of order of lipid acyl chains was investigated. Using 2H-NMR spectroscopy the effect of doxorubicin on mixed bilayers of DOPS, DOPA, dioleoylphosphatidylcholine (DOPC), and DOPE was studied. It was found that doxorubicin does not affect acyl chain order of pure zwitterionic phospholipids but dramatically influences that of anionic lipids [112]. At 25 °C, in bilayers consisting of 67... 

As a last comment, an attempt to dehydrocouple the labeled secondary silane, PhMeSiD2, to give D(PhSiMe)xD, with Cp2ZrCl2/2 BuLi demonstrated another process that was promoted by this catalyst system.50 Analysis of the oligomer mixture produced revealed that although each oligomer had approximately two deuterium atoms (determined by mass spectroscopy), the label had scrambled between the SiH and CH (methyl group) positions as determined by H and 2H NMR spectroscopy. 

SLR time results provide novel information on the temperature dependence and distribution of local RFs and their dynamics. A direct evidence for incoherent phonon-assisted deuteron tunnelling in H-bonded systems has been observed from NMR experiments. The use of quadrupole-perturbed ID 2H NMR spectroscopy and in particular 2D 2H NMR exchange spectroscopy has found to be very promising as regards elucidating the details of the hydrogen dynamics. 

Structures 13C, 2H and 2H NMR spectroscopy (T2 relaxation times, signal intensity ratio versus generation) rheology studies electron microscopy computer-assisted molecular simulations, comparison to CPK models electrospray mass spectroscopy fluorescence probe analysis. 

Iridium(O) nanoclusters reacted with imidazolium-based ILs under formation of imidazolylidenes [68]. The authors believed this reaction to be the reason for the high stability of nanoclusters in ILs. 2H NMR spectroscopy revealed incorporation of deuterium into all three positions at the imidazolium ring but only little deuterium incorporation into the alkyl chain. 

Group 18. - A 3He NMR study has been made of line-broadening in solid 3He-4He mixtures below 50 mK.571 2H NMR spectroscopy was used to study impurity-helium solids prepared by injecting deuterium atoms and mole-cules into superfluid He. Pulsed He NMR data were reported for solid He in a silver sinter down to temperatures of 400 pK.573 He NMR was used to characterise 3He nanoclusters embedded in h.c.p. 4He.574 Ferromagnetism of two-dimensional solid 3He has been investigated by SQUID NMR.575... 

The deuterium-labelled initiator method was also applied to the polymerization of macromonomer to determine the number of initiator fragments in a polymacromonomer chain (N) and initiator efficiency (/)-77 Isotactic and syndiotactic PMMA macromonomers having a styrene group as polymerizable function were polymerized with AIBN-<7 2 in toluene at 60°C and the resultant polymacromonomers were analysed by 2H NMR spectroscopy (Table 8). The N values were less than unity (0.50 0.72), indicating some kind of chain transfer reaction in the radical polymerization of macromonomer. The / values were 0.18 0.28 and much smaller than those for styrene polymerization (0.5 0.7). The isotactic macromonomer gave larger N and / values than the syndiotactic... 

Number of initiator fragment per polymacromonomer determined by 2H NMR spectroscopy. Initiator efficiency. 

The dynamics of the molecular rotation of 2-pyridone in toluene, carbon tetrachloride, methanol, and water have been investigated at 305 K by 13C and 2H NMR spectroscopy. Both chemical shifts and relaxation times show that it forms stable hydrogen-bonded complexes in methanol and in water, reorienting as a complete unit and taking with it two solvent molecules. These solvated species are stable within the liquid-state temperature range, and reorient according to the hydrodynamic law as indicated by the 14N line width measurements (85MRC460). 

Related studies have made use of 2H NMR spectroscopy in the solid state. The theoretical foundation for the study of dynamics in dihydrogen complexes was developed by Buntkowsky and coworkers.124 Solid-state 2H NMR spectroscopy has been used to study the dynamics of bound D2 in tntns- Ru( D2)CI(dppe)2 PI>, where evidence was found for coherent rotational tunneling, with a barrier of 6.2kcal/ mol.125 In more recent work, solid-state 2H NMR spectroscopy has been used to determine the structure and dynamics of several dihydrogen Ru complexes.126... 

When the line broadening becomes a serious obstacle, one can take advantage of a phenomenon that results in narrower lines. Specifically, substitution of1H atoms with the 2H isotope coupled with 2H NMR spectroscopy results in spectral lines that are up to 40 times narrower than those of corresponding ll NMR, due to slower nuclear relaxation of the 2H nuclei in paramagnetic compounds. 

In order to discriminate between both hypotheses PEIs having selectively deuterated spacers were synthesized (184-186). The deuterated spacers were prepared by Pt catalyzed deuteration of spacers containing a diacetylene unit in their midst. The deuterated PEIs were examined by 2H NMR spectroscopy in the... 

Another type of derivatized silica surface that has received considerable attention is Cis-derivatized silica gel that is, silica gel that has been silylated with reagents such as Cl(CH3)2Si(CH2)i7CH3 (45-51). This system was studied via 13C NMR (47) and 2H NMR spectroscopy (45) as a function of surface loading of the Cis chains and of certain added liquids. The ability of cross polarization to select static components of a surface derivative relative to more mobile components—which would be emphasized by non-CP (single-pulse) techniques that rely on direct 13C spin-lattice relaxation—can be seen in Figure 8, which provides a comparison between the single-pulse and cross-polarization 13C MAS NMR spectroscopy results on four Cis-silica samples. Dramatic differences in line shapes and intensities, which can be interpreted at least qualitatively in terms of... 

Dimitrova, G.T, Tadros, T.R, Luckham, P.R, Kipps, M.R. Investigations into the phase behavior of nonionic ethoxylated surfactants using 2H NMR spectroscopy. Langmuir 12, 315-318 (1996)... 

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