Characterization of Dynamics at the Solid-Liquid Interface via Dynamic Nuclear Polarization
Final Report Abstract
The project aimed at developing a new method to study interactions at the interface between a solid and a liquid. The main idea was based on Dynamic Nuclear Polarization, a method that makes use of organic radicals to enhance the Nuclear Magnetic Resonance (NMR) signal on target molecules in the solution. The spin polarization transfer from the electrons on the radical to the nuclei on the target molecule depends on the relative molecular motions that modulate the magnetic interaction between the two spins. During the funding period, we perfected a series of analytical tools to assess those dynamics from experimental data. With experimental studies on 13C, 19F, and 31P as target nuclei, we identify non-covalnt interactions (such as hydrogen bonds, nitrogen bonds, and Van der Waals) as one of the primary contributors to the DNP effect. We translated the same methodology to systems where the radical was immobilized on a surface. We tested both silica microbeads and gold nanoparticle functionalized with nitroxide radicals as prototype systems of a large class of hybrid (i.e. solid/liquid) materials. Despite the limited radical mobility hampers the efficiency of the polarization transfer, we could still observe sizeable enhancements on 13C nuclei. While the mechanistic investigation is still undergoing, we recognized that these systems can be effectively used as 'DNP sensors' due to their potential ability to hyperpolarize only certain types of molecules. Further studies in this direction are also ongoing.
Publications
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Theoretical analysis of scalar relaxation in 13C-DNP in liquids. Journal of Magnetic Resonance Open, 10-11, 100040.
Orlando, Tomas; Kuprov, Ilya & Hiller, Markus
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Large31P-NMR enhancements in liquid state dynamic nuclear polarization through radical/target molecule non-covalent interaction. Physical Chemistry Chemical Physics, 25(1), 822-828.
Reinhard, Maik; Levien, Marcel; Bennati, Marina & Orlando, Tomas
