Amplified Overhauser DNP with Selective Deuteration: Attenuation of Double-Quantum Cross-Relaxation
- Ravi Shankar Palani
- Michael MardiniMichael MardiniDepartment of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United StatesMore by Michael Mardini
- Leo Delage-Laurin
- Daniel Banks
- Yifu OuyangYifu OuyangDepartment of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United StatesMore by Yifu Ouyang
- Eric BryertonEric BryertonVirginia Diodes Corporation, Charlottesville, Virginia 22902, United StatesMore by Eric Bryerton
- James G. KempfJames G. KempfBruker Biospin Corporation, Billerica, Massachusetts 01821, United StatesMore by James G. Kempf
- Timothy M. Swager
- , and
- Robert G. Griffin*
We recently used selective 2H labeling of BDPA to investigate the Overhauser Effect (OE) dynamic nuclear polarization (DNP) mechanism in insulating solids doped with 1,3-bis(diphenylene)-2-phenylallyl (BDPA), and established that the α and γ 1H spins on the fluorene rings are responsible for generating a zero quantum (ZQ) mediated positive bulk polarization. Here, we establish that the phenyl 1H spins relax via double-quantum (DQ) processes and therefore contribute negative enhancements which attenuate the OE-DNP. With measurements at different magnetic field strengths, we show that phenyl-d5-BDPA offers >50% improvement in OE-DNP enhancement compared to h21-BDPA attaining a maximum of ∼90 at 14.1 T and 5 kHz MAS, the highest observed OE-DNP enhancement to date under these conditions. The approach may be utilized to optimize other polarizing agents exhibiting an OE, an important DNP mechanism with a favorable field and spinning frequency dependence.
This article is cited by 2 publications.
- Yifan Quan, Yifu Ouyang, Michael Mardini, Ravi Shankar Palani, Daniel Banks, James Kempf, W. Tom Wenckebach, Robert G. Griffin. Resonant Mixing Dynamic Nuclear Polarization. The Journal of Physical Chemistry Letters 2023, 14 (31) , 7007-7013. https://doi.org/10.1021/acs.jpclett.3c01869
- Ravi Shankar Palani, Michael Mardini, Yifan Quan, Robert G. Griffin. Dynamic nuclear polarization with trityl radicals. Journal of Magnetic Resonance 2023, 349 , 107411. https://doi.org/10.1016/j.jmr.2023.107411