Publisher’s Note: “Determining the geometry of strongly hydrogen-bonded silanols in a layered hydrous silicate by solid-state nuclear magnetic resonance” [J. Chem. Phys. 122, 054705 (2005)]

Étude par des expériences HETCOR 1H–29Si des interfaces tensioactif/silice dans des matériaux mésostructurés à porosité ordonnée

“…Ces sites Q 3 sont donc en interaction forte avec les protons de la tête polaire, comme l'atteste la seule corrélation mise en évidence clairement dans la carte HETCOR. On ne peut néanmoins pas exclure totalement la présence d'une minorité de sites Si-OH [33] qui apparaissent à t CP plus élevé à un déplace-ment chimique moins élevé que précédemment (d = 5,7 ppm) ; • à plus fort temps de contact (t CP = 5 ms), les répon-ses des deux systèmes ne sont pas très différentes. Les protons de la tête polaire se corrèlent, non seu- lement avec les sites Q 3 , mais également avec les sites Q 4 surtout dans le cas de MCM-41.…”

Probing Structural and Motional Features of the C-Terminal Part of the Human Centrin 2/P17-XPC Microcrystalline Complex by Solid-State NMR Spectroscopy

“…Consequently, the Fourier transform of the time dependence leads to dipolar spectra ( Figure 12, right) featuring modified Pake doublets due to the oscillating heteronuclear polarization transfer, while proton spin-diffusion leads to an isolated central peak. 23,16,49 It is worth pointing out that the dipolar spectra shown in Figure 12 are largely dominated by the most rigid C−H and N−H pairs in the 44 residues of the four α-helices which have larger splittings than the 23 residues of the two EF-hand loops and the central linker, while the terminal parts do not appear to contribute significantly. Further experimental evidence shows that the rf-field inhomogeneity has a negligible effect on the dipolar splittings at accurately determined n = ±1 Hartmann− Hahn conditions (see Figure S5, Supporting Information, for a comparison of the lineshapes recorded with a fully packed rotor and with a small sample placed in the central part of the rotor).…”

“…Numerical simulations were carried out with SPINE-VOLUTION 22 or by using an exact analytical treatment of isolated spin pairs under MAS including spin diffusion effects. 23 3. RESULTS AND DISCUSSION 3.1.…”

“…Experimental evidence was later presented showing that exp were extracted from the splittings multiplied by a factor of √2 to account for the n = −1 CP matching condition. Simulated build-up curves and corresponding dipolar spectra were obtained with the SPINEVOLUTION program 21 for isolated pairs of spins (in red), while the fitting of the experimental build-up curves and corresponding dipolar spectra (in blue) were obtained using the exact analytical treatment for isolated pairs of spins that includes spin diffusion effects 23 and implemented using the Scilab 50 software.…”

Solid state NMR spectroscopy

“…616 29 Si MAS NMR spectra were used to determine the geometry of strongly hydrogen-bonded silanols in octasilicate (RUB-18, layered hydrous silicate). 617 620 There have been solid-state NMR studies of composite materials based on SiO 2 -TiO 2 621-623 and SiO 2 -ZrO 2 . 624 29 Si MAS NMR spectra were used to determine the structures of glasses xPbO Á (100 À x)SiO 2 , where x = 25-89.…”