Rational design of dinitroxide biradicals for efficient cross-effect dynamic nuclear polarization

Dominik J Kubicki (1) , Gilles Casano (2) , Martin Schwarzwälder (3) , Sebastien ´ Abel (2) , Claire ´ Sauvée (2) , Karthikeyan Ganesan (4) , Maxim Yulikov (3) , Aaron J Rossini (5) , Gunnar J Jeschke (6) , Christophe ´ Copéret (3) , Anne Lesage (1) , Paul Tordo (7) , Olivier Ouari (2) , Lyndon Emsley (5)

1 Solid-State NMR Methods for Materials - Méthodes de RMN à l'état solide pour les matériaux
2 ICR - Institut de Chimie Radicalaire
3 Laboratory of Inorganic Chemistry
4 Association of Computer Electronics and Electrical Engineers (ACEEE)
5 EPFL - Ecole Polytechnique Fédérale de Lausanne
6 Laboratory of Physical Chemistry
7 SREP - Structure et Réactivité des Espèces Paramagnétiques

A series of 37 dinitroxide biradicals have been prepared and their performance studied as polarizing agents in cross-effect DNP NMR experiments at 9.4 T and 100 K in 1,1,2,2-tetrachloroethane (TCE). We observe that in this regime the DNP performance is strongly correlated with the substituents on the polarizing agents, and electron and nuclear spin relaxation times, with longer relaxation times leading to better enhancements. We also observe that deuteration of the radicals generally leads to better DNP enhancement but with longer build-up time. One of the new radicals introduced here provides the best performance obtained so far under these conditions.

Domaines: Chimie organique

Dominik J Kubicki, Gilles Casano, Martin Schwarzwälder, Sebastien ´ Abel, Claire ´ Sauvée, et al.. Rational design of dinitroxide biradicals for efficient cross-effect dynamic nuclear polarization. Chemical Science, 2016, 7 (1), pp.550 - 558. ⟨10.1039/C5SC02921J⟩. ⟨hal-01387080⟩