Physical Chemistry, Short talk
PC-016

Progress on photo-CIDNP as a General Tool for Dye Sensitized Hyperpolarization in Solid-state NMR

M. Visegrádi1, M. Levien1, F. De Biasi1, G. Karthikeyan2, J. W. Whipham1, O. Ouari2, L. Emsley1*
1Institut des Sciences et Ingenierie Chimiques, École Polytechnique Fedérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland, 2Aix-Marseille University, CNRS, Institut de Chimie Radicalaire, 13013 Marseille, France

NMR spectroscopy is an extremely versatile technique for atomic level structural investigation. One of the major disadvantages of NMR spectroscopy is its poor sensitivity, due to the low polarization of nuclear spin-flip transitions. To address this, throughout the past decades, significant advances have been made to hyperpolarize nuclear spins. 

Emerging pathways to generate bulk nuclear hyperpolarization are optically based techniques such as photochemically induced dynamic nuclear polarization (photo-CIDNP). Recently, we have shown that it is possible to generate bulk hyperpolarization using small donor-acceptor molecules (D-A) as polarizing agents (PAs).1,2 Following the initial demonstration of 1H bulk hyperpolarization at low magnetic field, we extended the approach through rational design of small D-A systems to magnetic fields as high as 21.15 T, reaching enhancements up to a factor of 100.3

Using our recently the kinetic photocycle description of solid-state photo-CIDNP,4 we report a new generation of photo-PAs, which yield enhancements significantly in excess of what we have previously reported. Moreover, we also present novel results on bulk 1H using standard DNP solvent formulations for generating 1H nuclear hyperpolarization. Furthermore, we will also discuss theoretical and experimental progress on understanding polarization trans-fer via spin diffusion to the bulk to increase bulk enhancements.

(1) De Biasi, F.; Hope, M. A.; Avalos, C. E.; Karthikeyan, G.; Casano, G.; Mishra, A.; Badoni, S.; Stevanato, G.; Kubicki, D. J.; Milani, J.; et al. Journal of the American Chemical Society 2023, 145 (27), 14874-14883.

(2) Brown, P. J.; Qiu, Y. F.; Latawiec, E. I.; Phelan, B. T.; Tcyrulnikov, N. A.; Palmer, J. R.; Krzyaniak, M. D.; Kopp, S. M.; Huang, Y. H.; Young, R. M.; et al. J Phys Chem A 2024, 128 (43), 9371-9382.

(3) De Biasi, F.; Karthikeyan, G.; Visegrádi, M.; Levien, M.; Hope, M. A.; Brown, P. J.; Wasielewski, M. R.; Ouari, O.; Emsley, L. J. Am. Chem. Soc. 2024, 146, 19667-19672.

(4) De Biasi, F.; Visegrádi, M.; Levien, M.; Chmelka, B. F.; Emsley, L. J Chem Phys 2025, 163 (24).