A general formulation for magnetic exchange coupling within long-distance radical ion pairs

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Abstract

A Hubbard model-based expression for the magnetic exchange interaction, 2J, between the spins of a radical ion pair is derived for a generic donor-bridge-acceptor (D- Bn -A) system in terms of the superexchange coupling, t, between molecular orbitals of the donor, bridge, and acceptor and the energies, ε, and same-site Coulomb repulsions, U, of these orbitals. The formulation is used to predict 2J for the photophysically well-characterized series phenothiazine- p- (phenylene)n -perylene diimide, n=2,3,4,5, where the superexchange coupling is calculated with multipathway, second- and third-order perturbation theory coupled with the extended Huckel formalism. U and ε are estimated through experimentally determined electrochemical potentials. Due to multiple interactions arising from the large distance between magnetic centers in these donor-bridge-acceptor systems, agreement with experiment was substantially improved when third-order corrections were included in the calculation of t and 2J.

Original languageEnglish
Article number064504
JournalJournal of Chemical Physics
Volume123
Issue number6
DOIs
Publication statusPublished - Aug 8 2005

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Exchange coupling
Ions
formulations
Perylene
phenothiazines
Hubbard model
ions
Exchange interactions
Molecular orbitals
molecular orbitals
perturbation theory
interactions
formalism
orbitals
Experiments
energy

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

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title = "A general formulation for magnetic exchange coupling within long-distance radical ion pairs",
abstract = "A Hubbard model-based expression for the magnetic exchange interaction, 2J, between the spins of a radical ion pair is derived for a generic donor-bridge-acceptor (D- Bn -A) system in terms of the superexchange coupling, t, between molecular orbitals of the donor, bridge, and acceptor and the energies, ε, and same-site Coulomb repulsions, U, of these orbitals. The formulation is used to predict 2J for the photophysically well-characterized series phenothiazine- p- (phenylene)n -perylene diimide, n=2,3,4,5, where the superexchange coupling is calculated with multipathway, second- and third-order perturbation theory coupled with the extended Huckel formalism. U and ε are estimated through experimentally determined electrochemical potentials. Due to multiple interactions arising from the large distance between magnetic centers in these donor-bridge-acceptor systems, agreement with experiment was substantially improved when third-order corrections were included in the calculation of t and 2J.",
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AU - Wasielewski, Michael R

AU - Ratner, Mark A

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N2 - A Hubbard model-based expression for the magnetic exchange interaction, 2J, between the spins of a radical ion pair is derived for a generic donor-bridge-acceptor (D- Bn -A) system in terms of the superexchange coupling, t, between molecular orbitals of the donor, bridge, and acceptor and the energies, ε, and same-site Coulomb repulsions, U, of these orbitals. The formulation is used to predict 2J for the photophysically well-characterized series phenothiazine- p- (phenylene)n -perylene diimide, n=2,3,4,5, where the superexchange coupling is calculated with multipathway, second- and third-order perturbation theory coupled with the extended Huckel formalism. U and ε are estimated through experimentally determined electrochemical potentials. Due to multiple interactions arising from the large distance between magnetic centers in these donor-bridge-acceptor systems, agreement with experiment was substantially improved when third-order corrections were included in the calculation of t and 2J.

AB - A Hubbard model-based expression for the magnetic exchange interaction, 2J, between the spins of a radical ion pair is derived for a generic donor-bridge-acceptor (D- Bn -A) system in terms of the superexchange coupling, t, between molecular orbitals of the donor, bridge, and acceptor and the energies, ε, and same-site Coulomb repulsions, U, of these orbitals. The formulation is used to predict 2J for the photophysically well-characterized series phenothiazine- p- (phenylene)n -perylene diimide, n=2,3,4,5, where the superexchange coupling is calculated with multipathway, second- and third-order perturbation theory coupled with the extended Huckel formalism. U and ε are estimated through experimentally determined electrochemical potentials. Due to multiple interactions arising from the large distance between magnetic centers in these donor-bridge-acceptor systems, agreement with experiment was substantially improved when third-order corrections were included in the calculation of t and 2J.

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