Session FOB. There are 3 abstracts in this session.



Session: Materials 3, time: 08:30am-09:10am

An atomistic view of catalysts using solid-state NMR


Raynald Giovine1; Julien Trébosc1; Frédérique Pourpoint1; Jean-Paul Amoureux1, 2; Olivier Lafon1, 3
1Univ. Lille, CNRS, ENSCL, UCCS, Lille, France; 2Bruker, Wissembourg, France; 3Institut Univ. de France, Paris, France
We show how advanced NMR techniques and instruments can provide new insights into the atomic-level structure of catalysts. We have notably introduced in recent years efficient and robust techniques to probe connectivities and proximities involving quadrupolar nuclei, such as <sup>17</sup>O, <sup>27</sup>Al, <sup>67</sup>Zn… These techniques can be combined with high magnetic fields and/or Dynamic Nuclear Polarization in order to improve their resolution and sensitivity. These innovative NMR approaches have notably been employed to observe the structure of the Brønsted acid sites in amorphous silica alumina, the synergy between active sites in Zn-modified zeolites, the oxygen sites at the surface of silica nanoparticles and the functionalization of fibrous silica nanoparticles to form solid base and photocatalysts. 

 

Session: Materials 3, time: 09:10am-09:50am

Paramagnetic Metal Ion Dopants for Endogenous Dynamic Nuclear Polarization    in the Bulk of Inorganic Solids   


Tamar Wolf1; Adi Harchol1; Sandeep Kumar2; Dan Major2; Michal Leskes1
1Weizmann Institute of Science, Rehovot, Israel; 2Bar Ilan University, Ramat Gan, Israel
Sensitivity enhancement in solid state NMR via dynamic nuclear polarization (DNP) is commonly based on the use of nitroxide biradicals as polarizing agents. In materials science, since the use of nitroxides often limits the signal enhancement to the materials’ surface and subsurface layers, there is need for hyperpolarization approaches which provide sensitivity in the bulk of micron sized particles. Recently, paramagnetic metal ions have emerged as an alternative.
Here I will present the remarkable efficacy of Mn(II) dopants, used as endogenous polarization agents for MAS-DNP, in enabling the detection of 17O at a natural abundance of only 0.038% in oxides. Furthermore, I will discuss the enhancements obtained for 6,7Li with various metal ion dopants in MAS-DNP experiments on battery materials.

Session: Materials 3, time: 09:50am-10:30am

Structure, Dynamics, and Symmetry. Electrophilic Interactions and   Chemical Bonds in Solid Materials Studied by Multinuclear Magnetic Resonance   


David Bryce
University of Ottawa, Ottawa, Canada

Recent advances are described in the context of two broad research themes: (a) non-covalent electrophilic interactions studied via solid-state NMR and (b) dynamics and equivalence from J splittings arising from pairs of quadrupolar nuclei in solids. We report on multinuclear powder and single-crystal solid-state magnetic resonance studies of a range of cocrystals and materials featuring halogen bonds, chalcogen bonds, pnictogen bonds, and tetrel bonds.  The work involves the examination of a variety of nuclides including 13C, 17O, 31P, 35/37Cl, 79/81Br, 127I, 77Se, 207Pb, 121/123Sb.  For example, 121/123Sb NQR studies of antimony in pnictogen-bonded cocrystals has led to a rudimentary implementation of ‘NQR crystallography’.  The roles of dynamics and crystallographic symmetry in the interpretation of the data are also highlighted.