TY - JOUR

T1 - Trityl-Aryl-Nitroxide-Based Genuinely g-Engineered Biradicals, As Studied by Dynamic Nuclear Polarization, Multifrequency ESR/ENDOR, Arbitrary Wave Generator Pulse Microwave Waveform Spectroscopy, and Quantum Chemical Calculations

AU - Sato, Kazunobu

AU - Hirao, Rei

AU - Timofeev, Ivan

AU - Krumkacheva, Olesya

AU - Zaytseva, Elena

AU - Rogozhnikova, Olga

AU - Tormyshev, Victor M.

AU - Trukhin, Dmitry

AU - Bagryanskaya, Elena

AU - Gutmann, Torsten

AU - Klimavicius, Vytautas

AU - Buntkowsky, Gerd

AU - Sugisaki, Kenji

AU - Nakazawa, Shigeaki

AU - Matsuoka, Hideto

AU - Toyota, Kazuo

AU - Shiomi, Daisuke

AU - Takui, Takeji

N1 - Publisher Copyright: Copyright © 2019 American Chemical Society.

PY - 2019/7/27

Y1 - 2019/7/27

N2 - Trityl and nitroxide radicals are connected by π-topologically controlled aryl linkers, generating genuinely g-engineered biradicals. They serve as a typical model for biradicals in which the exchange (J) and hyperfine interactions compete with the g-difference electronic Zeeman interactions. The magnetic properties underlying the biradical spin Hamiltonian for solution, including J's, have been determined by multifrequency CW-ESR and 1H ENDOR spectroscopy and compared with those obtained by quantum chemical calculations. The experimental J values were in good agreement with the quantum chemical calculations. The g-engineered biradicals have been tested as a prototype for AWG (Arbitrary Wave Generator)-based spin manipulation techniques, which enable GRAPE (GRAdient Pulse Engineering) microwave control of spins in molecular magnetic resonance spectroscopy for use in molecular spin quantum computers, demonstrating efficient signal enhancement of specific weakened hyperfine signals. Dynamic nuclear polarization (DNP) effects of the biradicals for 400 MHz nuclear magnetic resonance signal enhancement have been examined, giving efficiency factors of 30 for 1H and 27.8 for 13C nuclei. The marked DNP results show the feasibility of these biradicals for hyperpolarization.

AB - Trityl and nitroxide radicals are connected by π-topologically controlled aryl linkers, generating genuinely g-engineered biradicals. They serve as a typical model for biradicals in which the exchange (J) and hyperfine interactions compete with the g-difference electronic Zeeman interactions. The magnetic properties underlying the biradical spin Hamiltonian for solution, including J's, have been determined by multifrequency CW-ESR and 1H ENDOR spectroscopy and compared with those obtained by quantum chemical calculations. The experimental J values were in good agreement with the quantum chemical calculations. The g-engineered biradicals have been tested as a prototype for AWG (Arbitrary Wave Generator)-based spin manipulation techniques, which enable GRAPE (GRAdient Pulse Engineering) microwave control of spins in molecular magnetic resonance spectroscopy for use in molecular spin quantum computers, demonstrating efficient signal enhancement of specific weakened hyperfine signals. Dynamic nuclear polarization (DNP) effects of the biradicals for 400 MHz nuclear magnetic resonance signal enhancement have been examined, giving efficiency factors of 30 for 1H and 27.8 for 13C nuclei. The marked DNP results show the feasibility of these biradicals for hyperpolarization.

KW - SPIN NUTATION SPECTROSCOPY

KW - ELECTRONIC-STRUCTURES

KW - ENHANCED NMR

KW - RESONANCE

KW - EFFICIENT

KW - EXCHANGE

KW - EPR

KW - DIPOLAR

KW - ENDOR

KW - TRIRADICALS

UR - http://www.scopus.com/inward/record.url?scp=85071679850&partnerID=8YFLogxK

U2 - 10.1021/acs.jpca.9b07169

DO - 10.1021/acs.jpca.9b07169

M3 - Article

C2 - 31373818

AN - SCOPUS:85071679850

VL - 123

SP - 7507

EP - 7517

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

IS - 34

ER -