High-resolution MAS

A. Pampel, F. Volke 2003, (Studying lyotropic crystalline phases using high-resolution MAS NMR spectroscopy), in Lecture Notes in Physics, eds. R. Haber-landt, D. Michel, A. Poppl, R. Stannar-ius, Springer, Berlin. 

M. J. Shapiro, NMR methods, Analytical Techniques in Combinatorial Chemistry, 2000,77-111. M. J. Shapiro and J. S. Gounarides, High resolution MAS-NMR in combinatorial chemistry,... 

A. Meissner, P. Bloch, E. Humpfer, M. Spraul and O. W. Sorensen, Reduction of inhomogeneous line broadening in two-dimensional high-resolution MAS NMR spectra of molecules attached to swelled resins in solid-phase synthesis, J. Am. Chem. Soc., 1997, 119, 1787-1788. 

J. Chin, B. Fell, S. Pochapsky, M. J. Shapiro and J. R. Wareing, 2D SECSY NMR for combinatorial chemistry. High resolution MAS spectra for resin-bound molecules, J. Org. Chem., 1998, 63, 1309-1311. 

J. A. Chin, A. Chen and M. J. Shapiro, SPEEDY Spin-echo enhanced diffusion filtered spectroscopy. A new tool for high resolution MAS NMR, J. Comb. Chem., 2000, 2, 293-296. 

Shintu, L. and Caldarelli, S. (2005). High-resolution MAS NMR and chemometrics Characterization of the ripening of Parmigiano Reggiano cheese.. Agric. Food Chern. 53, 4026-4031. 

High resolution MAS techniques of 13C, DEPT, correlated spectroscopy (COSY), total correlation spectroscopy (TOCSY), heteronuclear chemical shift correlation (HETCOR) were used to examine conventional CBS and efficient TMTD vulcanisation of polybutadiene [37]. In conventional CBS vulcanisation, the major vulcanisate 13C NMR peak occurred at 44.9 ppm and was assigned to a trans allylic structure (-C=C-C-Sx with X=3 or 4). The efficient TMTD vulcanisation yielded as main product a 13C NMR peak at 54.0 ppm and was assigned to a cis allylic vulcanisate (-C=C-C-Sx x=l). While cyclic sulfur by-products were observed in both vulcanisation systems, the CBS formulations gave rise to a higher percentage postulated to be formed via a episulfide intermediate. 

Vulcanisate structures of BR crosslinked with cyclic disulfides was studied by NMR.36 Using high resolution MAS techniques of DEPT, COSY, TOCSY, and HETCOR, the resulting spectra showed that crosslinking gave an addition product to the double bond and not the allylic structure found in typical sulfur vulcanisations. 

Chain J, Fell B, Pochapsky S, Shapiro MJ, Wareing JR, 2-D SECSY NMR for combinatorial chemistry—High resolution MAS spectra for resin-bound molecules, 63 1309-1311, 1998. 

While specific applications of gel-phase NMR have been useful for SPS reaction monitoring, the great potential of SPS NMR is in the determination of structure and the measurement of purity and yields, especially through the use of magic angle spinning-high-resolution (MAS-HR) NMR techniques. This important topic will be addressed in Section 1.4.6. 

Tsang TM, Woodman B, McLoughlin GA, Griffin JL, Tabrizi SJ, Bates GP, Holmes E. Metabolic characterization of the R6/2 transgenic mouse model of Huntington s disease by high-resolution MAS IH NMR spectroscopy. J. Proteome Res. 2006 5 483-492. 

Resolution of the ZSM-12 Structure by X-ray Powder Data and High Resolution MAS NMR... 

The recent development of a gradient high-resolution MAS probe will extend the utility of 2D experiments by removing artifacts that generally accompany MAS 2D NMR data on resin samples (46). The lack of artifacts is illustrated by the high quality SECSY spectrum shown in Fig. 16. SECSY data contain the same information as a COSY spectrum, but the appearance of the spectrum is different. The diagonal lies along the FI =0 and the off-... 

Chemical shifts are extensively applied in the structure analysis of biomolecules in the solid state, being especially informative for biomembranes and fibres. There are two fundamentally distinct approaches of how either isotropic chemical shifts or chemical shift anisotropies, respectively, are utilized Isotropic chemical shifts of N or ll are typically available from high resolution MAS and can be correlated with the local chemical environment and geometry of the protein of interest, as outlined in detail above. Alternatively, aligned membranes or drawn fibres are ideally suited to prepare macroscopically oriented samples, in which the anisotropy of the... 

Three resonances corresponding to the three crystallographically distinct fluorine sites have been resolved in the high-resolution MAS spectrum of chiolite (Na5Al3Fi4) collected at a field strength of 19.6 T and at a spinning speed of 40 kHz. In contrast, only one broad resonance is observed in the F MAS NMR spectrum of the isostructural compound NasW309F5. Thus, a combination of F MAS, F CP, and Na- F HETCOR NMR experiments has been applied to resolve the resonances from the different local environments. 

Fig. 18.20. Fluorine high-resolution (MAS) spectrum of a commercial sample of Viton. Direct polarisation without proton decoupling was used. The asterisks indicate spinning sidebands. The spinning speed was 12 kHz. See the text for further details of the experimental conditions. The peak numbers are referred to in Table 18.2, which lists the assignments.

Figure 14 shows the high-resolution MAS Si-NMR spectra of Na-mordenite and its dealuminated counterparts. The spectrum of Na-Z consists of three resonance lines at -99, -105 and -110 ppm, corresponding to Si(2Al), Si(l Al) and Si(OAl) configurations respectively. In addition, silanol groups at defect lattice sites contribute to the intensity of the NMR line at -105 ppm. As dealumination proceeds, the lines at -99 and -105 ppm decrease, while the relative intensity of the -110 ppm line increases (Table V>. 

Figure 14. High-resolution MAS 29Si-NMR spectra of Na-Zeolon and its dealuminated forms. (Reproduced from ref. 19. Copyright 1986 American Chemical Society.)...

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