C Solid-State NMR

Baldock JA, Oades JM, Waters AG, Peng X, Vassallo AM, Wilson MA. Aspects of the chemical-structure of soil organic materials as revealed by solid-state C-13 NMR spectroscopy. Biogeochemistry 1992 16 1 42. 

As can be seen from Fig 2b, the solid state C-13 nmr spectrum of T. aestivum also shows sets of enhanced resonances at 61 ppm and 169.6-174.9 ppm respectively (24). However, their relative intensities are very different from that observed for L. leucocephala. Indeed, it can immediately be seen that very little reduction of the administered precursor to hydroxymethyl analogues (at 61 ppm) has occurred. On the other hand, the dominant resonances at 169.6 and 174.9 ppm are coincident with bound hydroxycin-namic acids (e.g. ferulic 5a) and its esters (31). Subsequent analysis of its isolated acetal lignin derivative (32) indicated that much of the lignin contained hydroxycinnamate residues (33). 

Garroway et al. 67) used solid state C-13 NMR studies on epoxy polymers to... 

Garroway, Ritchie, and Moniz 70 continued the characterization of epoxy polymers with respect to molecular motion using variable temperature, solid state C-13 NMR. DGEBA was the epoxy of interest. The DGEBA was cured with piperidine, m-phenylene diamine, hexahydrophthalic anhydride and nadic methyl anhydride. The piperidine cured DGEBA had the best resolved polymer spectra. This system... 

Cholli, Ritchey, and Koenig75 characterized the epoxy system DGEBA with solid state C-13 NMR. This study followed the disappearance of intensity of the epoxy carbons and the increase in intensity of the methylene carbons attached to the oxygen atoms. In Fig. 19, these intensity changes are plotted versus the curing time of the epoxy resins. Figure 20 plots the increase in methylene carbon intensities versus the decrease in epoxide group intensities. 

Kurosu H, Kawasaki M, Hirose M, Yamada M, Kang S, Thisayukta J, Sone M, Takezoe H (2004) Solid-state C-13 NMR study of chiral twisted conformation attributable to chirality in smectic phases of achiral banana-shaped molecules. J Phys Chem A 108 4674 -678... 

Figure 15.6. Example of 13C chemical shift assignments of structural groups found in NOM. The asterisk marks the C atom which is found in the corresponding chemical shift region. Reprinted from Keeler, C., Kelly, E. F., and Maciel, G. E. (2006). Chemical-structural information from solid-state C-13 NMR studies of a suite of humic materials from a lower montane forest soil, Colorado, USA. Geoderma 130,124-140, with permission from Elsevier.

Conte, P., Piccolo, A., Van Lagen, B., Buurman, P, and de Jager, P A. (1997). Quantitative aspects of solid-state C-13-NMR spectra of humic substances from soils of volcanic systems. Geoderma 80, 327-338. 

Smernik, R. J. (2005). Solid-state C-13 NMR spectroscopic studies of soil organic matter at two magnetic field strengths. Geoderma 125, 249-271. 

Smernik, R. J., and Oades, J. M. (2000a). The use of spin counting for determining quantitation in solid state C-13 NMR spectra of natural organic matter 1. Model systems and the effects of paramagnetic impurities. Geoderma 96,101-129. 

Solid state C-13 NMR spectra of amoxicillin trihydrate and other penicillins have been used to compare thiazolidine ring conformations in the solution and solid states [24], The results indicated rapid interconversion between the S out of plane and the C3 out of plane conformations in solution, with an equilibrium ratio of 74 to 26 for solutions of amoxicillin sodium salt. 

Atalla RH and VanderHart DL (1999) The role of solid state C-13 NMR spectroscopy in studies of the nature of native celluloses. Solid State Nuclear Magnetic Resonance, 75(1) 1-19... 

L Wallbacks, U Edlund, B Norden, and I Berglund. Multivariate Characterization of Pulp Using Solid-State C(13)-NMR, FTIR, and NIR [Near-IR Spectroscopy]. Tappi J. 74 201-206, 1991. 

Figure 1, Solid state C-13 NMR spectra (obtained at 37.7 MHz) of the cured epoxy resins with BDMA, after 1 hour curing, after 8 hours of curing. At top is the spectrum of the 1-hour cured sample under solution spectrometer conditions.

By using solid-state C-13 NMR spectroscopy, Koenig and his group (Koenig, 2000 Pellicioli et al., 2002) have added much detail to the chemical structure of the sulfurated network backbone. Following are the types of... 

Simmons, A. Ray, E. Jelinski, L.W. Solid-state C-13 Nmr of Nephia-clavipes dragline silk establishes structure and identity of crystalline regions. Macromolecules 27 5235-5237 (1994). 

This expectation is supported by the observations of the different trends of C-13 shift displacements in the high-resolution solid state C-13 NMR spectra of corresponding a-CD inclusion complexes[3]. In the solid-state, the a-CD complexation induced shifts are caused by transference of the guest molecule from the free state, surrounded by the same molecules, to the CD cavity. 

This observation has profound implications in the studies of host-guest (enzyme-substrate/inhibitor) recognition by solid state C-13 NMR. Further substantiation of this implication was therefore conducted. The most direct approach to perturb the dynamic ef ect... 

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