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Spinning Molecules, Spinning Spins: Modulation of an Electron Spin Exchange Interaction in a Highly Anisotropic Hyperfine Field.

Publication ,  Journal Article
Brugh, AM; Wang, R; Therien, MJ; Forbes, MDE
Published in: ACS omega
October 2021

An investigation of spin and conformational dynamics in a series of symmetric Cu-Cu porphyrin dimer solutions is presented using electron paramagnetic resonance (EPR) spectroscopy. Previous spectral simulations focused on the isotropic exchange interaction (Javg) between the Cu centers. In this work, an additional line broadening parameter (Jmod) is explored in detail via variable temperature X-band EPR in liquid solution for several different structures. The Jmod phenomenon is due to fluctuations in the spin exchange interaction caused by conformational motion of the porphyrin planes. The Jmod parameter scales with the inverse of the rotational barriers that determine the Boltzmann-weighted torsional angle distribution between neighboring porphyrin planes. Arrhenius plots allow for extraction of the activation energies for rotation, which are 5.77, 2.84, and 5.31 kJ/mol for ethyne-bridged (porphinato)copper(II)-(porphinato)copper(II), butadiyne-bridged (porphinato)copper(II)-(porphinato)copper(II), and ethyne-bridged (porphinato)copper(II)-(porphinato)zinc(II)-(porphinato)copper(II) complexes, respectively. DFT calculations of these torsional barriers match well with the experimental results. This is the first report of a Jmod analysis within a highly anisotropic hyperfine field and demonstrates the utility of the theory for extraction of dynamic information.

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Published In

ACS omega

DOI

EISSN

2470-1343

ISSN

2470-1343

Publication Date

October 2021

Volume

6

Issue

42

Start / End Page

27865 / 27873

Related Subject Headings

  • 4004 Chemical engineering
  • 3406 Physical chemistry
  • 3403 Macromolecular and materials chemistry
  • 0912 Materials Engineering
  • 0904 Chemical Engineering
 

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Brugh, A. M., Wang, R., Therien, M. J., & Forbes, M. D. E. (2021). Spinning Molecules, Spinning Spins: Modulation of an Electron Spin Exchange Interaction in a Highly Anisotropic Hyperfine Field. ACS Omega, 6(42), 27865–27873. https://doi.org/10.1021/acsomega.1c03490
Brugh, Alexander M., Ruobing Wang, Michael J. Therien, and Malcolm D. E. Forbes. “Spinning Molecules, Spinning Spins: Modulation of an Electron Spin Exchange Interaction in a Highly Anisotropic Hyperfine Field.ACS Omega 6, no. 42 (October 2021): 27865–73. https://doi.org/10.1021/acsomega.1c03490.
Brugh, Alexander M., et al. “Spinning Molecules, Spinning Spins: Modulation of an Electron Spin Exchange Interaction in a Highly Anisotropic Hyperfine Field.ACS Omega, vol. 6, no. 42, Oct. 2021, pp. 27865–73. Epmc, doi:10.1021/acsomega.1c03490.

Published In

ACS omega

DOI

EISSN

2470-1343

ISSN

2470-1343

Publication Date

October 2021

Volume

6

Issue

42

Start / End Page

27865 / 27873

Related Subject Headings

  • 4004 Chemical engineering
  • 3406 Physical chemistry
  • 3403 Macromolecular and materials chemistry
  • 0912 Materials Engineering
  • 0904 Chemical Engineering