Deuteron-NMR measurements

Komfield J.A., Spiess H.W., Nefzger H., Hayen H., and Eisenbach C.D. Deuteron NMR measurement of order and mobility in the hard segments of a model polyurethane, Macromolecules, 24, 4787, 1991. Meltzer A.D., Spiess H.W., Eisenbach C.D., and Hayen H. Motional behaviour within the hard domain of segmented polyurethane A NMR study of a triblock model system. Macromolecules, 25, 993, 1992. 

Deuteron -NMR measurements on the same system (labelled in the methyl group) also show that the mobility of the hydrophilic ammonium head group is reduced by... 

Given the structure in Fig. 2.3 as a prototype of the monolayer arrangement of adsorbed water on kaolinite group minerals, there remains only the question of its single-particle properties. Proton and deuteron NMR measurements are instructive in this respect.As indicated in Table 2.1, NMR line shapes show whether a preferred orientation of water molecules exists on the NMR time scale, and NMR relaxation data can yield a value for the rotational correlation time, In the case of 10-A halloysite, the NMR signal from water protons or deuterons in the... 

FIGURE 5.22 The segmental relaxation times for PEO neat (bold solid line) and in blends with PMMA (dashed lines) containing 3% to 30% PEO (from top to bottom) from deuteron NMR measurements. Fits to the data by the VET law given by Lutz et al. (2003) are shown but not the data themselves. Also shown is the independent relaxation time for PEO (dotted Une, using n = 0.5), which lies close to the characteristic time, tc = 2 ps. The most probable relaxation times calculated for a number of temperatures by the CM equation for concentrations of PEO at 3% (diamonds, n = 0.76), 10% (triangles, n = 0.75), and 30% (squares, n = 0.715), respectively. 

L. Vugmeyster, D. Ostrovsky, A. Khadjinova,. EUden, G.L. Hoatson, R.L. Void, Slow motions in the hydrophobic core of chicken villin headpiece subdomain and their contributions to configurational entropy and heat capacity from solid-state deuteron NMR measurements. Biochemistry 50 (2011) 10637—10646. 

The NMR measurements were performed on systems composed of ca. 25 wt. % samples of aPS (M = 6.6x 10 g/mol, PD = 1.1, Pressure Chemical Company) in either reagent grade toluene (Aldrich) or toluene-d0 (Aldrich). The protonated solvent was used for the diffusion measurements and the deuterated solvent for the relaxation studies. At this concentration, the Tg j for the system was determined to be about -65 °C (i). The NMR spectra were run on a JEOL FX-90Q NMR spectrometer operating at 90 and 14 MHz for protons and deuterons, respectively. The T and T2 measurements were made with the standard inversion-recovery and spin-echo (CPMG) sequences, respectively. 

Line shape studies of 7Rb and deuteron NMR lines have thrown more light on the frustration in the system. Blinc et al.5 have shown clearly the measurement of second moment can be related to the Edwards-Anderson spin-glass order parameter in the glass phase. 

Specific heat measurements40 indicate that the assumption of static frozen glass disorder at low temperatures may be too restrictive and that the intra-H-bond hydrogen motion may still persist in the form of quantum tunnelling. To check this hypothesis, 2D deuteron NMR and 87Rb and 2H SLR measurements were carried out at low temperatures. With site-specific NMR measurements, it was also hoped to identify the microscopic nature of the "two-level" states which determine the low T glassy properties of these systems. 

Peptides. The correlation of deuterium quadrupolar tensors by spin diffusion under slow magic-angle-spinning conditions can provide accurate measurements of their relative orientation. This work showed the technique applied to the cyclo-P-peptide cyclo[(5)- 3-homoalanyl-(R)-P-homoalanyl-(S)-P-homoalanyl-(i )-P-homoalanyl] with its amide hydrogens labeled by deu-terons. From the 2D spin-diffusion spectrum, the mutual orientation of the amide deuteron quadrupolar coupling tensors were found. Eight conformations that are all consistent with the NMR measurement were determined. 

NMR. Magnetic resonance experiments at low temperatures have been limited largely to proton and deuteron NMR of the water molecules in water-polymer preparations. This is reasonable because of the sensitivity attainable and because the most rapidly moving molecular species (water) is the most easily detected. I will discuss only systems without macroscopic order (e.g., frozen solutions of globular proteins) but the interested reader will find intriguing reports of nmr measurements on protein crystals and on fibrous or layered materials (15,16,17). 

Biehl et al.22 noted, however, that the proton hf couplings measured by ENDOR differed significantly (5-10%) from the corresponding values deduced via deuteron NMR, using the relationship. 

It is important to also note the application of deuteron NMR to multidimensional experiments involving dipolar interactions and imaging [139]. Schmidt et al [138] have recently presented a dipolar measurement... 

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