Dynamic Nuclear Polarization using Photoexcited Triplet Electron Spins in Eutectic Mixtures

Area of Science:

• Nuclear Magnetic Resonance Spectroscopy
• Quantum Chemistry

Background:

• Dynamic nuclear polarization (Triplet-DNP) enhances nuclear spin polarization at room temperature and low magnetic fields.
• Pentacene is an effective polarizing agent for Triplet-DNP, but its application is limited by the low dopability of certain target molecules.

Purpose of the Study:

• To demonstrate room temperature 1H and 13C hyperpolarization of eutectic mixtures containing pentacene and target molecules.
• To overcome the limitations of low pentacene dopability in specific molecules for Triplet-DNP.

Main Methods:

• Utilizing eutectic mixtures of deuterated benzoic acid doped with pentacene.
• Incorporating target molecules such as salicylic acid, nicotinic acid, or 2-naphthoic acid into the eutectic mixtures.
• Performing Triplet-DNP experiments at room temperature and 0.39 T.

Main Results:

• Successful room temperature 1H and 13C hyperpolarization was achieved for eutectic mixtures.
• The highest 1H polarization reached 1.2% for a salicylic acid eutectic mixture.
• This method enables hyperpolarization of molecules with previously low pentacene dopability.

Conclusions:

• The developed sample preparation method is crucial for expanding Triplet-DNP applications.
• This technique significantly broadens the scope of Triplet-DNP in chemical and biomedical analyses.
• Room temperature hyperpolarization is now feasible for a wider range of molecules.