Restoring symmetry in two-dimensional solid-state NMR correlation spectra

International audienc

Decoupling and recoupling in solid state NMR at very high spinning frequency and static fields (methodological aspects and applications)

PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Efficient heteronuclear decoupling by quenching rotary resonance in solid-state NMR

A method for heteronuclear decoupling in fast magic-angle spinning NMR measurements comprises application of a decoupling RF-pulse sequence with a decoupling-field amplitude 1⁄2 1 I on spins of a first nucleus and of an excitation pulse on spins of a second nucleus, the sequence comprising m blocks of pulses, with m ¥ 4, each block comprising an N-fold repetition of a pair of pulses with pulse width Ä p and phases whereby Ä p is equal for all pulses, whereby the phase of the pulse pair of the (i+1)-th block is inverted with respect to the pulse pair of the i-th block, with i=1 ... m-1 and i is an odd number, whereby the pulses within each pair are phase inverted, whereby a phase shift is carried out after each j-th block, with j is an even number. The efficiency of the inventive method compares favourably with CW, TPPM, SPINAL and XiX decoupling methods at medium and high RF amplitudes, particularly under rotary resonance conditions

Exploitation de l'anisotropie de déplacement chimique pour l'étude de la géométrie moléculaire et des contacts intermoléculaires par résonance magnétique nucléaire à l'état solide

Ce mémoire traite de l'étude de la géométrie moléculaire et de la nature des contacts intermoléculaires dans les solides organiques et inorganiques grâce à des méthodologies appropriées. La première partie introduit de manière succincte les différentes notions de RMN à l'état solide utilisées dans ce travail. Dans un deuxième chapitre, l'évolution des valeurs principales du tenseur d'écran du carbone-13 et du phosphore-31 au cours de la déprotonation d'acides carboxyliques et de phosphates est corrélée avec leur état d'ionisation, leur conformation et la nature des interactions intermoléculaires dans lesquelles ils sont engagés. Le troisième chapitre est consacré à la caractérisation de la liaison hydrogène forte impliquant les silanols de deux polysilicates de sodium hydratés, grâce à l'emploi de méthodes complémentaires telles que la dynamique de polarisation croisée 1H-29Si et la modulation dipolaire de l'anisotropie de déplacement chimique du 29Si à faible fréquence de rotation.This work presents various methodologies to probe the molecular geometry and the nature of intermolecular contacts in organic and inorganic solids. The first part gives a brief description of basic principles of solid-state NMR that are used through these studies. In the second part, the variation of chemical shielding tensor principal values of carboxy carbon-13 and phosphate phosphorus-31 upon deprotonation is correlated with ionisation state, conformation and nature of the intermolecular interactions. The third part deals with the characterisation of the strong hydrogen bond involving the silanols of sodium hydrous polysilicates, using complementary methods such as 1H-29Si cross-polarisation dynamics and dipolar modulation of the 29Si chemical shift anisotropy at slow spinning frequency.NANCY1-SCD Sciences & Techniques (545782101) / SudocSudocFranceF

Broadband magnetization transfer using moderate radio-frequency fields for NMR with very high static fields and spinning speeds

We introduce a new dipolar recoupling scheme, dubbed PARIS-xy (phase-alternated recoupling irradiation scheme using orthogonal radio-frequency phases), to promote efficient broadband magnetization exchange between C-13 nuclei using moderate radio-frequency amplitudes at very high magnetic field strengths and spinning speeds. Experimental observations for a wide range of spinning frequencies 30 <= nu(rot) <= 60 kHz and magnetic field strengths (B-0 = 9.4, 17.6 and 21.2 T) are backed up by numerical simulations. (C) 2010 Elsevier B. V. All rights reserved

Low-power decoupling at high spinning frequencies in high static fields

We demonstrate that heteronuclear decoupling using a Phase-Inverted Supercycled Sequence for Attenuation of Rotary Resonance (PISSARRO) is very efficient at high spinning frequencies (v(rot) = 60 kHz) and high magnetic fields (900 MHz for protons at 21 T) even with moderate radio-frequency decoupling amplitudes (v(1)' = 15 kHz), despite the wide range of isotropic chemical shifts of the protons and the increased effect of their chemical shift anisotropy. (C) 2009 Elsevier Inc. All rights reserved

Efficient heteronuclear decoupling by quenching rotary resonance in solid-state NMR

We propose a new scheme for heteronuclear decoupling designed for fast magic-angle spinning (MAS), dubbed phase-inverted supercycled sequence for attenuation of rotary resonance (PISSARRO). Its efficiency compares favourably with CW, TPPM, SPINAL and XiX decoupling methods at medium and high RF amplitudes, particularly under conditions where the efficiency of decoupling is affected by undesired rotary resonance effects