Hyperpolarizing Small Molecules using Parahydrogen and Solid-State Spin Diffusion.

Area of Science:

• Magnetic Resonance Spectroscopy
• Hyperpolarization Techniques
• Solid-State Chemistry

Background:

• Parahydrogen-induced polarization (PHIP) offers inexpensive hyperpolarization but is limited by its reliance on specific chemical reactions with H2.
• Existing PHIP methods require direct interaction with hydrogen gas, restricting their general applicability.

Purpose of the Study:

• To develop a novel method, PHIP-SSD, to expand the scope of PHIP hyperpolarization.
• To enable hyperpolarization of target molecules not directly involved in the initial PHIP reaction.

Main Methods:

• Utilizing PHIP to generate a hyperpolarized source molecule ([1-13C]-fumarate).
• Employing solid-state spin diffusion to transfer polarization from the source to target molecules.
• Dissolving the polarized target molecules for solution-state NMR applications.

Main Results:

• Demonstrated successful polarization transfer from [1-13C]-fumarate to various 13C-labeled target molecules.
• Achieved 13C polarizations ranging from 0.01% to 3% for [1-13C]-benzoic acid.
• Obtained 100-200 fold signal enhancements for [13C,15N2]-urea, [1-13C]-pyruvate, and [1-13C]-benzoic acid using simple powder grinding.

Conclusions:

• PHIP-SSD effectively transfers hyperpolarization via solid-state spin diffusion, broadening PHIP's utility.
• The method does not require specific co-crystallization, allowing for facile hyperpolarization of diverse molecules.
• PHIP-SSD presents a promising strategy for accessible hyperpolarization based on PHIP.