Rationalization of solid-state NMR multi-pulse decoupling strategies: Coupling of spin I = ½ and half-integer quadrupolar nuclei

Cassandre Kouvatas (1) , Nasima Kanwal , Julien Trébosc (2) , Claire Roiland (1) , Laurent Delevoye (3) , Sharon Ashbrook (4) , Eric Le Fur (1) , Laurent Le Pollès (1)

1 ISCR - Institut des Sciences Chimiques de Rennes
2 Université de Lille, Sciences et Technologies
3 UCCS - Unité de Catalyse et Chimie du Solide - UMR 8181
4 School of Chemistry [University of St Andrews]

In this paper we undertake a study of the decoupling efficiency of the Multiple-Pulse (MP) scheme, and a rationalization of its parameterization and of the choice of instrumental set up. This decoupling scheme is known to remove the broadening of spin-1/2 spectra I, produced by the heteronuclear scalar interaction with a half-integer quadrupolar nucleus S, without reintroducing heteronuclear dipolar interaction. The resulting resolution enhancement depends on the set-up of the length of the series of pulses and delays of the MP, and some intrinsic material and instrumental parameters. Firstly through a numerical approach, this study investigates the influence of the main intrinsic material parameters (heteronuclear dipolar and J coupling, quadrupolar interaction, spin nature) and instrumental parameters (spinning rate, pulse field strength) on efficiency and resolution enhancement of the scalar decoupling scheme. A guideline is then proposed to obtain quickly and easily the best resolution enhancement via the rationalization of the instrumental and parameter set up. It is then illustrated and tested through experimental data, probing the efficiency of MP-decoupling set up using this guideline. Various spin systems were tested (P-V in VOPO, P-Nb in NbOPO, Sn-O in YSnO), combined with simulations results.

Mots clés: half integer quadrupolar nucleus; simulations; characterization of inorganic materials; resolution improvement; heteronuclear scalar interaction; Solid state NMR; Multi-Pulse decoupling

Domaines: Catalyse; Cristallographie; Chimie inorganique; Matériaux; Chimie théorique et/ou physique

Cassandre Kouvatas, Nasima Kanwal, Julien Trébosc, Claire Roiland, Laurent Delevoye, et al.. Rationalization of solid-state NMR multi-pulse decoupling strategies: Coupling of spin I = ½ and half-integer quadrupolar nuclei. Journal of Magnetic Resonance, 2019, 303, pp.48-56. ⟨10.1016/j.jmr.2019.04.005⟩. ⟨hal-02113808⟩