C NMR Spectra of Solids

The linewidth that one would obtain if one tried to measure C NMR spectra of solid samples in the same way as liquid samples would be approximately 20,000 Hz. This linewidth is approximately equivalent to the total chemical shift range for most organic compounds. Therefore it is apparent that it is not possible to obtain useful chemical shift information in this way. 

Figure 2. Scalar decoupled (yHt/2ir = 4 kHz) 50.3-MHz C NMR spectra of solid Hytrel and polybutylene terephthalate. Key a, Hytrel 4056 b, Hytrel 5526 c, Hytrel 6346 d, Hytrel 7246 and e, polybutylene terephthalate. All spectra were obtained on the same amount of polymer and were recorded at 34°C with 1024 accumulations and a 3 s pulse repetition rate. Peaks marked with X arise from an internal capillary containing benzene-df...

Application of high-power H-DD and rapid MAS techniques to record the C-NMR spectra of solid polymers can produce high-resolution spectra. However, to practically achieve signally averaged, pulsed FT spectra, the rate at which signal averaging can be repeated or the pulse repetition rate is dictated by the spin-lattice relaxation times, T, ... 

By combining the three previously described experiments into one grand experiment, high-resolution C-NMR spectra of solids can be obtained [5]. The... 

Fig. 9.17. CP-MAS C-NMR spectra of solid (Val) . Spectrum a is of the a form, and spectrum b is of the 0 form. Peak labels are as follows Ca, backbone carbons in valine Cp, side chain carbons in valine Cyiy2, carbons in side chain of valine. (Reproduced with permission from Ref. [42]. 1981.)...

Table 1. 13-C chemical shifts (relative to TMS) from CP/MAS NMR spectra of solid cellulose polymorphs Ref.15>...

Figure 8. High resolution CP/MA.S solid state C-NMR spectra of tetrapropyl- and tetrabutylammonium ions in ZSM-5 and ZSM-11 zeolites respectively. 11 Reproduced with permission from Ref. 11 Copyright 1981, Butterworth and Co (Publishers) Ltd c ".

The C chemical shifts of benzotriazole in the solid state are obtained using the CP-MAS technique. The chemical shifts are slightly different from those observed in DMSO-dg or CDCI3 <83H(20)1713>. CP-MAS C NMR spectroscopy is a powerful tool which enables determination of the tautomeric structure of benzotriazole in the solid state. Thus, the solid-state C NMR spectra of some A-(dialkylaminomethyl)benzotriazoles support the existence of only the N(l) isomer <87JCS(P1)2673>. 

Figure 7. One-pulse solid-state C NMR spectra of H2, H5, and H15 (10-80 ppm). The disappearance of the -CHj-peak indicates that the mobility is greatly reduced when the ratio TMP bis-MPA is increased.

Figure 2.18 MAS NMR spectra of solids (A) Al spectrum of zeolite Y at 23.5 MHz and at 104.2MHz note the spectral improvement at higher field (B) B spectrum of Corning 7070 glass at 128.4 MHz (c) spectrum of Pb(N03)2 at 83.4 MHz (the broader spectrum above is without spinning) (D) spectrum of NH4 at 40.5 MHz. The magnified NOj spectrum is also shown. (After...

Fig. 8 12-MHz MAS CP DD 13 C NMR spectra of a solid poly(cyclopentyl methacrylate), b poly(cyclohexyl methacrylate) and c poly(cycloheptyl methacrylate) (from [6])...

Fig. 6. 9F NMR spectra of solid type fluoride (A) prepared at 50=C (B) prepared at 9CFC (C) prepared at 110 C. (Quoted from H. Fujimoto, A. Mabuchi, T. Maeda, Y. Matsumura, N. Watanabe, H. Touhara, Carbon, 30 (1992) 851, with permission).

Fig. 8.10. Chemical shifts from NMR spectra of solid and molten silicates. L indicates liquid at temperature shown G indicates glass and C, crystalline solid. Arrows indicate linewidth (not errors) (after Stebbins et al., 1985 reproduced with the publisher s permission).

Stoltz, M., Oliver, D. W., Wessels, P. L. and Chalmers, A. A. (1991). High resoluhon solid state C NMR spectra of mofebutazone, phenylbutazone and oxyphenbuta-zone in relation to X-ray crystallographic data. /. Pharm. ScL, 80, 357-62. [140]... 

Fig. 18 Solid-state C NMR spectra of ampicillin samples. (Adapted from Ref...

Figure 5.16 A) Solid state CPMAS- C-NMR spectra of crystalline and microcrystalline N-octyl-D-gluconamide (= d-GIu-8) materials are well-resolved. The signals have been assigned by considering gauche effects and by comparisons with solution state NMR spectra. The chemical shifts in the first spectrum correspond to an all-anti conformation, shifts in the second spectrum to a gauche bend (b). The methyl carbon C-8 signal indicates a polar environment oriented for the monolayer crystal a), and an unpolar environment for the bilayer crystal b) and micellar fibre c). The signals for the lyophilizedfibre in the third spectrum are somewhat broadened, but the shift of the C-2 signals can be clearly detected. This points to a G conformation (b).

Solid-state C NMR spectra of the high molecular weight (HMW) fraction (> 1000 Da) of DOM isolated from surface (10 m) and interior (750 m) ocean water from the Gulf of Mexico (from Dr R. Benner, unpublished). Observed shifts indicate large concentrations of carbohydrates (70-1 10 ppm) that decrease with depth, whereas very little aromatic carbon is observed. Most of the uncharacterized fraction in HMW DOM consists of alkyl carbon (0-45 ppm) at a 2 1 atomic basis with carboxyl carbon. 

Figure 3, Solid-state 13 C-NMR spectra of kerogen and coal samples from Upper Devonian black shales (right) and from other locations as indicated (left).

Differences in the C chemical shifts between rhodopsin and retinal PSB model compounds reveal the regions of the chromophore where changes occur in the retinal s structure or environment. Figure 39 presents several solid-state C NMR spectra of rhodopsin that illustrate the resolution and sensitivity which can be obtained by using MAS methods. 

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