A Factor Two Improvement in High-Field Dynamic Nuclear Polarization from Gd(III) Complexes by Design

Area of Science:

• Magnetic Resonance Spectroscopy
• Coordination Chemistry
• Materials Science

Background:

• Gadolinium(III) complexes show promise as polarizing agents in dynamic nuclear polarization (DNP) NMR spectroscopy.
• Optimizing ligand design is crucial for enhancing DNP performance.

Purpose of the Study:

• To investigate a novel gadolinium(III) complex, [Gd(tpatcn)], for high-field DNP NMR spectroscopy.
• To evaluate the impact of reduced zero-field splitting (ZFS) on DNP enhancement.

Main Methods:

• Synthesis and characterization of the [Gd(tpatcn)] complex.
• Assessment of its water solubility and line-narrowing properties.
• Measurement of magic-angle-spinning DNP enhancement at 9.4 T and 100 K.

Main Results:

• The [Gd(tpatcn)] complex demonstrated a stable, water-soluble, and narrow-line profile.
• A quadratic improvement in DNP enhancement was observed.
• The [Gd(tpatcn)] complex doubled the DNP enhancement compared to the state-of-the-art [Gd(dota)(H2O)]-.

Conclusions:

• Tailoring ligand design to minimize ZFS in gadolinium(III) complexes leads to significant DNP improvements.
• [Gd(tpatcn)] represents a new benchmark for polarizing agents in DNP NMR spectroscopy.
• This advancement holds potential for broader applications of DNP NMR.