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Article Dans Une Revue Physical Chemistry Chemical Physics Année : 2024

AsymPol-TEKs as efficient polarizing agents for MAS-DNP in glass matrices of non-aqueous solvents

Rania Harrabi
  • Fonction : Auteur
Shadi Alarab
Satyaki Chatterjee
Krishna K Damodaran
Johan van Tol
Daniel Lee
Subhradip Paul
Gaël de Paëpe
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Résumé

Two polarizing agents from the AsymPol family, AsymPol-TEK and cAsymPol-TEK (methyl-free version) are introduced for MAS-DNP applications in non-aqueous solvents. The performance of these new biradicals is rationalized in detail using a combination of electron paramagnetic resonance spectroscopy, density functional theory, molecular dynamics and quantitative MAS-DNP spin dynamics simulations. By slightly modifying the experimental protocol to keep the sample temperature low at insertion, we are able to obtain reproducable DNP-NMR data with 1,1,2,2-tetrachloroethane (TCE) at 100 K, which facilitates optimization and comparison of different polarizing agents. At intermediate magnetic fields, AsymPol-TEK and cAsymPol-TEK provide 1.5 to 3-fold improvement in sensitivity compared to TEKPol, one of the most widely used polarizing agents for organic solvents, with significantly shorter DNP buildup times of B1 s and B2 s at 9.4 and 14.1 T respectively. In the course of the work, we also isolated and characterized two diastereoisomers that can form during the synthesis of AsymPol-TEK; their difference in performance is described and discussed. Finally, the advantages of the AsymPol-TEKs are demonstrated by recording 2D 13C–13C correlation experiments at natural 13C-abundance of protondense microcrystals and by polarizing the surface of ZnO nanocrystals (NCs) coated with diphenyl phosphate ligands. For those experiments, cAsymPol-TEK yielded a three-fold increase in sensitivity compared to TEKPol, corresponding to a nine-fold time saving.

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hal-04500679 , version 1 (12-03-2024)

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Paternité - Pas d'utilisation commerciale

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Rania Harrabi, Thomas Halbritter, Shadi Alarab, Satyaki Chatterjee, Malgorzata Wolska-Pietkiewicz, et al.. AsymPol-TEKs as efficient polarizing agents for MAS-DNP in glass matrices of non-aqueous solvents. Physical Chemistry Chemical Physics, 2024, 26 (6), pp.5669-5682. ⟨10.1039/d3cp04271e⟩. ⟨hal-04500679⟩
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