Nuclear magnetic resonance proton decoupling

B.A. Berkowitz, J.J.H. Ackerman, Proton decoupled fluorine nuclear-magnetic-resonance spectroscopy in situ, Biophys. J. 51 (1987) 681-685. 

Solid-state C variable-amplitude cross polarization magic-angle spinning (VACP/MAS) nuclear magnetic resonance (NMR) spectra were acquired for the sorbitol samples. Proton decoupling was achieved by a two-pulse phase modulation (TPPM) sequence. Identical C spectra were measured for the y-form sorbitol samples, and a representative spectrum is shown in Figure 9. 

Wilson, M. A., and Goh, K. M. (1977). Proton-decoupled pulse Fourier-transform 13C nuclear magnetic resonance of soil organic matter. J. Soil Sci. 28, 645-652. 

Nuclear magnetic resonance spectroscopy has emerged as the most powerful tool for elucidating the molecular structures of cyclophos-phazene derivatives in solution. Proton NMR spectroscopy has been widely used because of its easy accessibility. The recent development of sophisticated instrumental facilities and the application of broadband proton decoupling have greatly improved the quality and usefulness of the 31P spectra (252) of cyclophosphazenes, and it is likely that this technique will become increasingly popular in the future. Fluorine NMR studies are useful for deducing the structures of fluorocyclophosphazenes, and the potential of this technique has been demonstrated in recent years (209, 210, 213, 307, 308, 343). 

Fig. 1. —Nuclear Magnetic Resonance Spectrum of lA3,4-Tetra-0-acetyl-5-[(ben-zyloxycarbonyI)amino]-5-deoxy-a-D-xylopyranose (207). (Taken at 100 MHz in chloroform at 35° acetyl protons omitted the decoupled signals are indicated above tetra-methylsilane as internal standard.)...

The carbon nuclear magnetic resonance spectrum of lomefloxacin mesylate obtained in D2O at 25°C is given in Figure 7 (9). The spectrum was obtained on a Bruker AM-500 NMR Spectrometer operating at 125.76 MHz and was referenced to external TSP [3-(trimethylsilyl)propionic-2,2,3,3-d4 acid]. The 13C spectrum was obtained with proton broad-band decoupling and the carbon assignments for lomefloxacin were made using a combination of 1-D and 2-D NMR techniques. 

E. Vinogradov. P. K. Madhu and S. Vega, Proton spectroscopy in solid state nuclear magnetic resonance with windowed phase modulated Lee-Goldburg decoupling sequences. Chem. Phys. Lett., 2002, 354, 193-202. 

Maciel, G. E., Bartuska, V. J., and Miknis, F. P. (1979). Characterization of organic material in coal by proton-decoupled C nuclear magnetic resonance with magic angle spinning. Fuel 58, 391-394. 

Nuclear Magnetic Double Resonance Nuclear Magnetic Resonance Nuclear Overhauser Effect Proton Noise Decoupling Rhamnopyranose Selective Frequency Decoupling Single Frequency Off-Resonance Decoupling... 

J. B. Grutzner and R. E. Santini, "Coherent broad-band decoupling — an alternative to proton noise decoupling in carbon-13 nuclear magnetic resonance spectroscopy, J. Magn. Resonance 19, 173-187 (1971). 

Figure 3.26 Homonuclear decoupling experiments of the 300 MHz proton NMR spectrum of sucrose dissolved in DjO. The fully coupled spectrum is shown in (c). (a) Selective saturation of the triplet at 4.05 ppm collapses the doublet at 4.22 ppm, showing the coupling between the positions of protons a and b marked on the sucrose structure, (b) Saturation of the doublet at 5.41 ppm collapses the doublet of doublets. The experiment shows the coupling between the protons marked c and d on the structure. (The spectra are from Petersheim, M., Nuclear magnetic resonance, in Ewing, G.A., ed.. Analytical Instrumentation Handbook, 2nd edn., Marcel Dekker Inc., New York, 1997. Used with permission. The sucrose structure is that of D-(-r)-sucrose, obtained from the SDBS database, courtesy of the National Institute of Industrial Science and Technology, Japan, http //www.aist.go.jp/RICBD/SDBS. Accessed on May 11, 2002.)...

Stereosequences in PLAs are routinely determined by the examination of nuclear magnetic resonance (NMR) spectra, particularly with regard to the NMR methine resonance and the proton decoupled NMR methine resonance. Figure 25.4 shows the possible PLA tetrad stereosequences (/ = isotactic dyad = syndiotactic dyad). The original ( C and H) NMR peak assignments for tactic PLAs were put forward at the tetrad level of sensitivity by Kricheldorf et al. based... 

---