Mixed-Valence Compounds as Polarizing Agents for Overhauser Dynamic Nuclear Polarization in Solids*

Area of Science:

• Solid-state Nuclear Magnetic Resonance (NMR) Spectroscopy
• Materials Science
• Physical Chemistry

Background:

• Dynamic Nuclear Polarization (DNP) enhances NMR signal sensitivity.
• Conventional DNP methods face challenges in solid-state applications, particularly at high magnetic fields.
• Mixed-valence compounds exhibit unique properties including persistent molecular mobility in solid matrices.

Purpose of the Study:

• To investigate mixed-valence compounds as novel polarizing agents for solid-state DNP NMR.
• To demonstrate the efficacy of these agents in high-field Overhauser-DNP experiments.
• To leverage the inherent molecular mobility of mixed-valence compounds for improved DNP performance.

Main Methods:

• Theoretical calculations to model compound behavior.
• Experimental validation of polarizing agent performance.
• High-field dynamic nuclear polarization Nuclear Magnetic Resonance (DNP NMR) experiments in the solid state.

Main Results:

• Mixed-valence compounds were identified as effective polarizing agents.
• Successful demonstration of Overhauser-DNP in the solid state using these agents.
• Favorable conditions for dynamic nuclear polarization formation were observed at ultra-high magnetic fields.

Conclusions:

• Mixed-valence compounds represent a promising new class of polarizing agents for solid-state DNP NMR.
• The persistent molecular mobility in these solids is key to their effectiveness.
• These findings open avenues for enhanced sensitivity in high-field solid-state NMR studies.