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NMR signals, Dramatically Boosted

Dabney and Cox view from the Brickyard. Students walking to class on North Campus.
Students walk to class on North Campus at the Brickyard, near the space where Harrelson Hall used to be.

Learn how NC State researchers demonstrated how NMR signals are dramatically boosted via simple visible light excitation.

Felix Castellano, Thomas Theis, and co-workers are deviating from the traditional approaches to overcome a significant weakness of Nuclear Magnetic Resonance (NMR) signals. As a scalable and fast method, they use hyperpolarization by simple visible light excitation to increase NMR sensitivity. A recent issue of ACS Central Science highlighted their research in an editorial titled “para-Hydrogen-Induced Polarization Enabled by Visible Light Activation.” 

A graphic representation illustrating the purpose of the research.
With visible light, the authors showed significant increases in NMR signal. They used light to energize a photosensitizer, which can transfer energy to a catalyst (top right in the circle). The catalyst adds a form of hydrogen gas (top left of circle) to an organic molecule (bottom of circle). This reaction forms a new molecule with a high NMR signal, as seen on the right side of the diagram.

A current graduate student of Chemistry at NC State University, Emily Brown, is the first author of the paper of interest. “NMR spectroscopy is used in the chemistry field to determine the structure of molecules,” said Brown. “NMR also measures signals using the same principle as Magnetic Resonance Imaging (MRI). Therefore, enhancing NMR sensitivity by using visible light is the starting point to the potential development of applications that could impact the future of chemistry and medicine.”

The authors compared the effects of visible light, UV light, and darkness on the signal (left of the diagram), showing that either form of light significantly increased the signal. They were also able to track the reaction (top center) and show where the catalyst added the hydrogen by both their measurements (bottom center) and computer simulations (far right).

The paper, “Triplet Photosensitized para-Hydrogen Induced Polarization,” appears in the November 23 issue of ACS Central Science. Castellano and Theis are the corresponding authors. Brown is the first author. Mandzhieva and TomHon are co-authors. 

DOI: 10.1021/acscentsci.2c01003