Phenylazide Hybrid-Silica – Polarization Platform for Dynamic Nuclear Polarization at Cryogenic Temperatures

Wolfram R Grüning , Harald Bieringer , Martin Schwarzwalder (1) , David Gajan (2) , Aurélien Bornet (3) , Basile Vuichoud (4) , Jonas Milani (3) , David Baudouin (5) , Laurent Veyre (5) , Anne Lesage (2) , Sami Jannin (3) , Geoffrey Bodenhausen (6) , Chloé Thieuleux (5) , Christophe Copéret (1)

1 Laboratory of Inorganic Chemistry
2 ISA - Centre de RMN à très hauts champs
3 ISIC - Institut des sciences et d'ingénierie chimiques
4 ISA - Hyperpolarized Magnetic Resonance
5 C2P2 - Laboratoire de Chimie, Catalyse, Polymères et Procédés, R 5265
6 Institut des Sciences et Ingénierie Chimiques

Hyperpolarization of NMR-active nuclei is key to gather high quality spectra of rare species and insensitive isotopes. We have recently established that silica-based materials containing regularly distributed nitroxyl radicals connected to the silica matrix by flexible linkers can serve as promising polarization matrices in DNP. Here we investigate the influence of the linker on the efficiency of the polarization. The materials were fully characterized and exhibit high surface areas and narrow pore size distributions with a tunable amount of phenyl azide groups over a broad range of concentrations. The phenyl azide groups can be easily functionalized via a two-step procedure into 4-carboxy-2,2,6,6-tetramethyl-1-oxyl-piperidine (TEMPO) to give polarizing matrices with controllable radical content. The DNP efficiency was found to be similar as in materials with flexible linkers, both for MAS at 105 K and dissolution DNP at 4 K.

Domaines: Chimie

Wolfram R Grüning, Harald Bieringer, Martin Schwarzwalder, David Gajan, Aurélien Bornet, et al.. Phenylazide Hybrid-Silica – Polarization Platform for Dynamic Nuclear Polarization at Cryogenic Temperatures. Helvetica Chimica Acta, 2017, 100 (1), pp.e1600122. ⟨10.1002/hlca.201600122⟩. ⟨hal-01838493⟩