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

Kazunobu Sato, Rei Hirao, Ivan Timofeev, Olesya Krumkacheva, Elena Zaytseva, Olga Rogozhnikova, Victor M. Tormyshev, Dmitry Trukhin, Elena Bagryanskaya, Torsten Gutmann, Vytautas Klimavicius, Gerd Buntkowsky, Kenji Sugisaki, Shigeaki Nakazawa, Hideto Matsuoka, Kazuo Toyota, Daisuke Shiomi, Takeji Takui

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)7507-7517
Number of pages11
JournalJournal of Physical Chemistry A
Volume123
Issue number34
DOIs
Publication statusPublished - 27 Jul 2019

Keywords

  • SPIN NUTATION SPECTROSCOPY
  • ELECTRONIC-STRUCTURES
  • ENHANCED NMR
  • RESONANCE
  • EFFICIENT
  • EXCHANGE
  • EPR
  • DIPOLAR
  • ENDOR
  • TRIRADICALS

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