L3C CP/MAS spectra

The l3C CP MAS spectra of the sample-A show the presence of the most prominent peak at 27.2 ppm for Ci carbon atom adjacent to the SH group and C2 carbon atom of the 3-mercaptopropyl group. There was another minor intensity broad peak at around 22.3 ppm which is assigned to C and C2 carbon atoms of the dipropyl disulfide. The presence of dipropyl disulfide in the sample A may be due to oxidative dehydrogenation of two adjacent thiol groups leading to the formation of disulfide (S-S) group. An unresolved shoulder down field to the C3 carbon of the thiol was observed for the C3 carbon of the dipropyl disulfide. Similar results were obtained by Lim et al. [6],... 

Fig. 13. 90.5-MHz 13C CP/MAS spectra of allyl-/-l3C alcohol (spectra a and b) and propanal-I-13C (spectra c and d) on zeolite FIZSM-5. All the spectra were acquired at ambient temperature (a) after heating for 5 h at 323 K (b) after heating at 393 K for 0.5 h (c) prior to heating (d) after heating at 353 K for 0.5 h. The downfield spectral features in spectra c and d, e.g., the isotropic shifts and the number of resonances, are consistent with those derived from allyl-/-l3C alcohol on HZSM-5 (spectra a and b), thus providing unambiguous evidence that the disputed resonance at 216 ppm is propanal-7-l3C. See Xu et at. (Ill) for a more detailed assignment of the resonances.

Kg. 35. l3C CP MAS NMR spectra and peak assignments of a cured polystyrylpyridine resin. Stick spectra are drawn from 13C NMR spectra of the model compounds CTC and BP2 in solution (reprinted from Ref. 2391 with permission)... 

Fig. 43. Transformation of protonated ethanol dimer in HjPWuO, by heat treatment. Solid-state l3C CP/MAS NMR spectra were obtained by using high purity, 3C ethanol (a) Dimer, (b) 333 K, (c) 343 K, (d) 363 K, (e) 373 K, (f) 423 K. Reprinted with permission from Ref. 169. Copyright 1992 American Chemical Society.

Figure 15.21. CP/MAS spectra l3C inp-dimethoxybenzene (note splitting induced in ortho carbons due to the asymmetry of the methoxy group), 29Si in poly-[dimethy lsiloxane) (PDMS), and 31P in bone mineral [roughly equivalent to Ca50H(P04)3]. (29Si spectrum reprinted with permission from Beshah K, Mark JE, Himstedt A, Ackerman JL. Characterization of PDMS model junctions and networks by solution and solid state silicon-29 NMR spectroscopy. J Polymer Sci B Polymer Phys. 1986 24 1207-1225. Copyright 1986 John Wiley Sons.)...

In general, l3C CP/MAS techniques depend on the mathematical manipulation which is employed to enhance the resolution of solid state NMR coal spectra.27 The several methods that have been implemented include ... 

Fig. 13. Comparison of l3C CP-MAS NMR (left) and DD-MAS NMR spectra (right) of D85N mutant (black traces) and wild type (dotted traces).153 Reproduced with permission from the Biophysical Society.

Fig. 6. CP-MAS l3C-NMR spectra of polydimethylsiloxane at 75.47 MHz above and below the melting transition. Chemical shifts refer to TMS = 0 ppm and correspond to the scale at the bottom (Ref.10))...

Fig. 8. Slow exchange-fast exchange transition for the conformational interconversion of crystalline cyclotetraeicosane in CP-MAS l3C-NMR spectra at 75.47 MHz. Chemical shifts refering to TMS = 0 ppm and temperatures in K are indicated at the spectra. (Ref.7 )...

Infrared spectra of the unfilled and filled copolymers were measured using a Perkin-Elmer model 1700 FTIR spectrometer. The 13C CP/MAS NMR measurements were conducted on a Bruker 300 instrument operating at 75.51 MHz. The samples were rotated with a spectra width of 40.0 Hz, the CP time was 5 ms. l3C lI distortionless enhancement by polarization transfer (DEPT) technique was applied for analysis of monomers. The process was performed at 75.51 MHz, rotated with a spectral width of 0.75 Hz and a CP time of 15 ms. Atomic force microscopy measurements were carried out using a Nanoscope Ilia controlled Dimension 3000 AFM (Digital Instrument, Santa Barbara, CA). 

Figure 7-13. Crossplot of broadline H and CP-MAS (narrow line) l3C spectra for a 43% mixture of erucamide with i-PP. Erucamide is a fatty acid amide used with PP film to reduce adhesion of adjacent layers of film. The contours indicated by arrows are due to polypropylene -CH3, >CH- and -CH2- groups, respectively. This shows that the >CH- group at 26 ppm on the 13C resonance axis has the lowest mobility, as its proton resonance is the broadest. [Adapted from I. Quijada-Garrido, M. Wilhelm, H. W. Spiess, J. M. Barrales-Rienda, Macromol. Chem. Phys. 199, 985 (1998). Copyright 1998, Wiley Periodicals, Inc., A Wiley Company.]...

Fig. 9. I3C DD-MAS (A) and CP-MAS (B) NMR spectra of [2-l3C]Ala-labeled bacteriorhodopsin.81 I3C NMR signals resonating at the loop region are from Ala residues in the C terminal a-helix, because those from the loop are completely suppressed.81 Reproduced with permission from the Japanese Biochemical Society.

Fig. 20. I3C CP-MAS (left) and DD-MAS (right) NMR spectra of [3-l3C]Ala-labeled bacteriorhodopsin recorded at various ionic strengths.104 Reproduced with permission from Blackwell Science Ltd.

Fig. 26. I3C CP-MAS NMR spectra of [l-l3C]Val-labeled wild type (A) and D85N (B and D) and D85N/D96N (C and E) recorded at pH 7 and 10. It is noteworthy that the arrowed peaks from the transmembrane helices are displaced to higher frequencies by protonation of Asp 85 at neutral pH and suppressed at pH 10 taking the M-like state.117 The peak at 177.81 ppm is ascribed to Val 213.88 Reproduced with permission from the American Chemical Society.

Fig. 27. I3C DD-MAS NMR spectra of enzymatically cleaved [3-l3C]Ala-labeled C-2 fragment (1-71) incorporated into the DMPC bilayer (A) and lipids from Halobacterium (B) with reference to the CP-MAS NMR spectrum of intact bacteriorhodopsin.16...

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