High-resolution solid-state MAS

High resolution solid-state MAS Ge NMR spectra of organogermanium compounds have been observed for the first time the chemical shifts and linewidths of tetraphenylgermane (38) and tetrabenzylgermane (137) were recorded with and without high-power decoupling. ... 

P-40 - High-resolution solid state MAS NMR studies on the role of promoter (phosphate) in the nucleation and crystallization of Silicalite -1 (Si-MFI)... 

Lain et al. have reported three-dimensional deuterium-carbon correlation experiments for high-resolution solid-state MAS NMR speetroseopy of large proteins.It has been shown that well-resolved eorrelation... 

In 2002, Goward et al. carried out the first study of proton conductivity using the high-resolution solid-state MAS NMR [25], They characterized the ethylene oxide tethered imidazole heterocycles by variable temperature experiments, as well as 2D homonuclear DQ NMR and 2D exchange spectroscopy (EXSY). The MAS NMR identified three types of hydrogen-bonded N—resonances, and DQ NMR identified hydrogen-bonded protons which are mobile on the time scale of the experiment and participate in proton transport. The local mobifity of protons was characterized by spin—spin relaxation times as a function of temperature,... 

Paramagnetic Probes in High-Resolution Solid-State MAS NMR. 175... 

KokotaMo GT, Fyfe CA, Kennedy GJ, Gobbi GC, Strobl H, Pasztor CT, Barlow GK, Bradley S (1986) Zeolite structural investigations by high resolution solid state mas nmr. In Murakami Y, lijima A, Ward JW, New developments in zeolite science and technology. Kodansha, Tokyo, Elsevier, Amsterdam, p 361... 

Fyfe et al. (155) measured high-resolution solid-state 27A1 MAS NMR spectra of a number of zeolites at 104.22 MHz. All the spectra contained one narrow peak with a chemical shift ranging, in different materials, from 51.5 to 65.0 ppm from A1(H20) + (see Table XIII). In dealuminated zeolites an additional signal was observed corresponding to six-coordinated Al in the zeolitic channels. 

This work foreshadows one way in which mechanistic studies of conventional (heterogeneous) and biological catalysts may proceed in future. When one recognizes that parallel H and 2H CP/MAS NMR studies could also be carried out in situ, there are good prospects that kinetic isotope effects will prove directly accessible through the agency of high-resolution solid-state NMR. 

Carbon black filled NR vulcanisates have been studied by high-resolution solid-state 13C NMR at 75.5 MHz. It is shown that the detection of poly- and mono-sulfidic crosslinks with 13C MAS spectroscopy is also possible in the case of carbon black filled NR vulcanisates. Quantitative results suggest that the addition of carbon black leads to a decrease in crosslink density with increasing filler content [55]. 

Klinowski and coworkers were the first to undertake a study of intercalates of water (D2O) and fullerene Qq by of high resolution Solid State NMR [75]. The authors confirmed that the C60/D2O intercalate presents a dynamical system and equilibrates in a matter of hours to the 17-day stable form. MAS spectra of the Q0/D2O intercalate do not show a single resonance at 144.0 ppm, as for pure fullerene, because of the intercalated gases, and possibly perdeuter-ated water, both affecting the chemical shift. The room temperature MAS... 

Finally, the CP/MAS spectrum of inclusion compounds with 1,9-dichlorononane is shown in Fig. 32c. In this case, the multiplicity of the host carbonyl signal at 190 ppm is six, and the host methyl signal at 26 ppm is also split into six signals. The splitting pattern suggests that there are two host molecules in the asymmetric unit. These results clearly prove that examination of high-resolution solid state NMR spectra can give information about the contents of the asymmetric unit and has potential for the analysis of polycrystalline solids. 

In the heterocycle 16, P and Se high-resolution solid-state NMR spectroscopy was used to study structural properties. Both P CP/MAS and Se CP/ MAS experiments revealed that the asymmetric unit consists of two independent molecules with a different geometry around phosphorus and selenium centres. The established values of anisotropy and asymmetry parameters reflected the distortion of the phosphorus environment, and correlated with X-ray diffraction data. P NMR spectroscopy has been used to follow a new type of P-decomposi-tion in diphosphorylated amines and to characterise new organophosphorus compounds with -N-P(0)-N- linkages. A series of dioxaphosphocin-6-oxides (17), of varying substituent X, have been characterised by using P NMR and... 

---