Dynamic Nuclear Polarization Using Electron Spin Cluster

Raj K. Chaklashiya; Asif Equbal; Andrey Shernyukov; Yuanxin Li; Karen Tsay; Quentin Stern; Victor Tormyshev; Elena Bagryanskaya; Songi Han

doi:10.1021/acs.jpclett.4c00182

Dynamic Nuclear Polarization Using Electron Spin Cluster

Raj K. Chaklashiya^*, Asif Equbal^*, Andrey Shernyukov^*, Yuanxin Li^*, Karen Tsay^*, Quentin Stern^*, Victor Tormyshev^*, Elena Bagryanskaya^*, Songi Han^*

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

Abstract

Dynamic nuclear polarization (DNP) utilizing narrow-line electron spin clusters (ESCs) to achieve nuclear spin resonance matching (ESC-DNP) by microwave irradiation is a promising way to achieve NMR signal enhancements with a wide design scope requiring low microwave power at high magnetic field. Here we present the design for a trityl-based tetra-radical (TetraTrityl) to achieve DNP for ¹H NMR at 7 T, supported by experimental data and quantum mechanical simulations. A slow-relaxing (T_1e ≈ 1 ms) 4-ESC is found to require at least two electron spin pairs at <8 Å e-e spin distance to yield ¹H ESC-DNP enhancement, while squeezing the rest of the e-e spin distances to <12 Å results in optimal ¹H ESC-DNP enhancements. Fast-relaxing ESCs (T_1e ≈ 10 μs) are found to require a weakly coupled narrow-line radical (sensitizer) to extract polarization from the ESC. These results provide design principles for achieving a power-efficient DNP at high field via ESC-DNP.

Original language	English (US)
Pages (from-to)	5366-5375
Number of pages	10
Journal	Journal of Physical Chemistry Letters
Volume	15
Issue number	20
DOIs	https://doi.org/10.1021/acs.jpclett.4c00182
State	Published - May 23 2024

Funding

We acknowledge the invaluable funding received from the National Science Foundation Grant CHE CMI #2004217 and the National Institute of General Medical Sciences MIRA Grant (Project #5R35GM136411-04) for the development of the dual DNP-EPR instrumentation. Synthesis of Monotrityl and TetraTrityl was supported by the Russian Ministry of Science and Higher Education grant to V.T. and E.B. (14.W03.31.0034). The contribution from A.E. was also supported by Tamkeen under the NYU Abu Dhabi Research Institute grant CG008. A.E. also thanks High Performance Computing facilities of New York University Abu Dhabi. The authors thank Dr. Kan Tagami for help with the 7 T DNP experiments and Vishnu Vijayan and Dr. Tom Casey for their help with EPR measurements. The authors give special thanks to Celeste Tobar for helping run the CW EPR measurements of TetraTrityl ( Figure S4 ). The authors also thank Dr. Alexander Maryasov for fruitful discussions.

ASJC Scopus subject areas

General Materials Science
Physical and Theoretical Chemistry

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title = "Dynamic Nuclear Polarization Using Electron Spin Cluster",

abstract = "Dynamic nuclear polarization (DNP) utilizing narrow-line electron spin clusters (ESCs) to achieve nuclear spin resonance matching (ESC-DNP) by microwave irradiation is a promising way to achieve NMR signal enhancements with a wide design scope requiring low microwave power at high magnetic field. Here we present the design for a trityl-based tetra-radical (TetraTrityl) to achieve DNP for 1H NMR at 7 T, supported by experimental data and quantum mechanical simulations. A slow-relaxing (T1e ≈ 1 ms) 4-ESC is found to require at least two electron spin pairs at <8 {\AA} e-e spin distance to yield 1H ESC-DNP enhancement, while squeezing the rest of the e-e spin distances to <12 {\AA} results in optimal 1H ESC-DNP enhancements. Fast-relaxing ESCs (T1e ≈ 10 μs) are found to require a weakly coupled narrow-line radical (sensitizer) to extract polarization from the ESC. These results provide design principles for achieving a power-efficient DNP at high field via ESC-DNP.",

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doi = "10.1021/acs.jpclett.4c00182",

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AU - Equbal, Asif

AU - Shernyukov, Andrey

AU - Li, Yuanxin

AU - Tsay, Karen

AU - Stern, Quentin

AU - Tormyshev, Victor

AU - Bagryanskaya, Elena

AU - Han, Songi

PY - 2024/5/23

Y1 - 2024/5/23

N2 - Dynamic nuclear polarization (DNP) utilizing narrow-line electron spin clusters (ESCs) to achieve nuclear spin resonance matching (ESC-DNP) by microwave irradiation is a promising way to achieve NMR signal enhancements with a wide design scope requiring low microwave power at high magnetic field. Here we present the design for a trityl-based tetra-radical (TetraTrityl) to achieve DNP for 1H NMR at 7 T, supported by experimental data and quantum mechanical simulations. A slow-relaxing (T1e ≈ 1 ms) 4-ESC is found to require at least two electron spin pairs at <8 Å e-e spin distance to yield 1H ESC-DNP enhancement, while squeezing the rest of the e-e spin distances to <12 Å results in optimal 1H ESC-DNP enhancements. Fast-relaxing ESCs (T1e ≈ 10 μs) are found to require a weakly coupled narrow-line radical (sensitizer) to extract polarization from the ESC. These results provide design principles for achieving a power-efficient DNP at high field via ESC-DNP.

AB - Dynamic nuclear polarization (DNP) utilizing narrow-line electron spin clusters (ESCs) to achieve nuclear spin resonance matching (ESC-DNP) by microwave irradiation is a promising way to achieve NMR signal enhancements with a wide design scope requiring low microwave power at high magnetic field. Here we present the design for a trityl-based tetra-radical (TetraTrityl) to achieve DNP for 1H NMR at 7 T, supported by experimental data and quantum mechanical simulations. A slow-relaxing (T1e ≈ 1 ms) 4-ESC is found to require at least two electron spin pairs at <8 Å e-e spin distance to yield 1H ESC-DNP enhancement, while squeezing the rest of the e-e spin distances to <12 Å results in optimal 1H ESC-DNP enhancements. Fast-relaxing ESCs (T1e ≈ 10 μs) are found to require a weakly coupled narrow-line radical (sensitizer) to extract polarization from the ESC. These results provide design principles for achieving a power-efficient DNP at high field via ESC-DNP.

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Dynamic Nuclear Polarization Using Electron Spin Cluster

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