Investigating the efficiency of silica materials with wall-embedded nitroxide radicals for dynamic nuclear polarisation NMR - Aix-Marseille Université Access content directly
Journal Articles Physical Chemistry Chemical Physics Year : 2022

Investigating the efficiency of silica materials with wall-embedded nitroxide radicals for dynamic nuclear polarisation NMR

Abstract

Dynamic nuclear polarisation (DNP) can significantly enhance the sensitivity of solid-state nuclear magnetic resonance (SSNMR) experiments by transferring the electron spin polarisation of paramagnetic species to nuclei through microwave irradiation of the sample at cryogenic temperatures. Paramagnetic species required for DNP can be provided in the form of mesoporous silica materials containing nitroxide radicals either located on the porous surface or embedded in the pore walls. The present study focuses specifically on porous materials with wall-embedded radicals that were synthesised using conventional molecular imprinting protocols. More remarkably, by changing the molecular structure of the TEMPO precursor, the theoretical distance between the oxygen atoms in a pair of wall-embedded face-to-face TEMPO radicals was increased stepwise (0.7, 0.9, 1.1, 1.3 and 1.5 nm). The thermal activation of these five series of materials led to 37 TEMPO-functionalised silica materials with different radical concentrations. Their efficiency as DNP polarising agents was subsequently investigated at 9.4 T and ~110 K under magic-angle spinning conditions (10 kHz) after impregnating them at room temperature with an aqueous solution of isotopically enriched proline. Our results show that the highest DNP efficiency was obtained for the silica materials that exhibited the shortest theoretical oxygen-oxygen distance between the TEMPO rings, suggesting that the design rules accepted for soluble DNP polarising agents may not be transposed to these materials with wall-embedded pairs of nitroxides.
Fichier principal
Vignette du fichier
PDN Full PCCP-HAL.pdf (317.74 Ko) Télécharger le fichier
Origin : Publication funded by an institution

Dates and versions

hal-03844800 , version 1 (09-11-2022)

Licence

Attribution - NonCommercial

Identifiers

Cite

Eric Besson, Aurelien Vebr, Fabio Ziarelli, Emily Bloch, Guillaume Gerbaud, et al.. Investigating the efficiency of silica materials with wall-embedded nitroxide radicals for dynamic nuclear polarisation NMR. Physical Chemistry Chemical Physics, 2022, 24 (41), pp.25279-25286. ⟨10.1039/D2CP02872G⟩. ⟨hal-03844800⟩
46 View
16 Download

Altmetric

Share

Gmail Facebook X LinkedIn More