Cross-polarization-magic angle structural analysis

Cross-Polarization-Magic Angle Spinning Carbon-13 NMR Approach to the Structural Analysis of Cellulose... 

The primary components and the chemical structure of the raw peat and the solid product were further analyzed by Fourier transform infrared spectroscopy (FTIR) 0ASCO 670 Plus) using the Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) technique and the JASCO IR Mentor Pro 6.5 software for spectral analysis. The cross polarization/magic angle spinning (CP/MAS) NMR spectrum of raw peat and the solid... 

This is the most promising nondegradative technique for humic structural analysis. This is primarily due to two fundamental instrumental advances the Fourier transform technique and the cross-polarization/ magic-angle spinning (CP/MAS) technique which allows the acquisition of NMR spectra from solid samples. The H and NMR spectra of all humic substances are highly resolved and exhibit several peaks. 

An extensive study was conducted on the effect of chemical and structural aspects of zeolites on the fire performance of the intumescent system, ammonium polyphosphate-pentaerythritol (APP-PER), where a marked improvement of the fire-retardant properties within different polymeric matrices has been observed.56 58 The synergistic mechanism of zeolite 4A with the intumescent materials was investigated using solid-state NMR. Chemical analysis combined with cross-polarization dipolar-decoupled magic-angle spinning NMR revealed that the materials resulting from the thermal treatment of the APP-PER and APP-PER/4A systems were formed by carbonaceous and phosphocarbonaceous species, and that the zeolite enhances the stability of the phosphocarbonaceous species. 

Cisproline(i-l)-aromatic(i) interactions have been detected in several short peptides in aqueous solution by analysis of anomalous chemical shifts measured by H-NMR. Conformational preferences of esters of 2,2,5,7,8-penta-methylchroman-6-ol were studied by dynamic C NMR in solution and the cross-polarization (CP)-magic angle spinning (MAS) technique in the solid phase. Experimental untilsyn ratios, N NMR chemical shift, and UV) and theoretical [DFT, MP2 and QCISD(T) calculations of optimized structures and untilsyn ratios and free energy differences, and GIAO calculation of NMR chemical shifts] results establish the conformations of iS-nitrosothiols. The formation of the cytosine-uracil (C-U) base pair in a duplex was observed in... 

C-n.m.r. analysis. The magic-angle spinning, cross-polarization C-n.m.r. spectrum of D-threo-2,5-hexodiulose in the solid state gave results which could be directly correlated with atomic positions previously found in an X-ray crystallographic analysis. The compound is a dimer (10), a structure which n.m.r. shows to be the predominant form in DMSO. 

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