Dendritic polarizing agents for DNP SENS

Wei-Chih Liao (1) , Ta-Chung Ong (1) , David Gajan (2) , Florian Bernada (3) , Claire Sauvée (3) , Maxim Yulikov (1) , Margherita Pucino (1) , Roman Schowner (4) , Martin Schwarzwälder (1) , Michael R Buchmeiser (4) , Gunnar Jeschke (1) , Paul Tordo (3) , Olivier Ouari (3) , Anne Lesage (2) , Lyndon Emsley (5) , Christophe Copéret (1)

1 ETH Zürich - Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich]
2 Solid-State NMR Methods for Materials - Méthodes de RMN à l'état solide pour les matériaux
3 ICR - Institut de Chimie Radicalaire
4 Inst Polymerchem
5 EPFL - Ecole Polytechnique Fédérale de Lausanne

Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an effective method to significantly improve solid-state NMR investigation of solid surfaces. The presence of unpaired electrons (polarizing agents) is crucial for DNP, but it has drawbacks such as leading to faster nuclear spin relaxation, or even reaction with the substrate under investigation. The latter can be a particular problem for heterogeneous catalysts. Here, we present a series of carbosilane-based dendritic polarizing agents, in which the bulky dendrimer can reduce the interaction between the solid surface and the free radical. We thereby preserve long nuclear T'2 of the surface species, and even successfully enhance a reactive heterogeneous metathesis catalyst.

Domaines: Chimie analytique

Wei-Chih Liao, Ta-Chung Ong, David Gajan, Florian Bernada, Claire Sauvée, et al.. Dendritic polarizing agents for DNP SENS. Chemical Science, 2017, 8 (1), pp.416-422. ⟨10.1039/c6sc03139k⟩. ⟨hal-01546474⟩